Patent Publication Number: US-9420987-B2

Title: Stethoscope head

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a United States national phase application of co-pending international patent application number PCT/CN2013/074794, filed Apr. 26, 2013, which claims priority to Chinese patent application number 201220214856.5, filed May 15, 2012, and Chinese patent application number 201210148071.7, filed May 15, 2012, the disclosures of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a medical instrument accessory, in particular to an accessory of a stethoscope, and more particularly to a stethoscope head. 
     TECHNICAL BACKGROUND 
     High density materials such as copper (with a density of 8.9 g/cm 3 ), titanium alloy (with a density of 7.82 g/cm 3 ), steel or particularly stainless steel (with a density of 7.8 g/cm 3 ), and zinc alloy (with a density of 6.58 g/cm 3 ) can conduct sounds with a fast speed and low attenuation, and the conducted sounds can be clearly heard, thus a stethoscope head in the prior art is typically made of the high density materials. However, the high density materials are expensive in price, heavy in weight, and monotonous in color, therefore, the stethoscope head is inconvenient in use. 
     Further, considering that the stethoscope head is generally made of the high density materials such as titanium alloy, copper and stainless steel, cutting tools used for machining such stethoscope head have a very high cost and the time taken for the machining is long, thus the stethoscope head is costly, thereby greatly increasing consumer costs. 
     Furthermore, the stethoscope head in the prior art is formed integrally and has a shape similar to a waist drum, that is, both ends of the stethoscope head are larger than the middle part of the stethoscope head, and a mold cannot be stripped in mold casting the stethoscope head, thus the stethoscope head can only be made by a milling process at a low working efficiency. 
     SUMMARY OF THE INVENTION 
     The present invention provides a stethoscope head which is light in weight, low in cost and does not affect the listening experience. 
     The present invention further provides a method for reducing a weight of a stethoscope head. 
     The present invention is realized as below. 
     A stethoscope head, where the stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body and intercommunicated with each other, at least a portion of the head body is made of a second density material, a density of a sound guiding layer on the sound collecting surface is larger than that of the second density material. 
     Further, a density of a sound guiding layer in the sound guiding pore is larger than that of the second density material, also, the density of the sound guiding layer in the sound guiding pore is the same as or different from that of a sound guiding layer on the sound collecting surface. 
     Furthermore, the head body is separated and includes an upper head body and a lower head body which are mutually fitted with each other, the sound collecting surface includes an upper sound collecting surface disposed on the upper head body and a lower sound collecting surface disposed on the lower head body, the upper sound collecting surface is communicated with the lower sound collecting surface through the sound guiding pore, the sound guiding pore is communicated with the lateral sound guiding aperture, the lower head body is made of the same material as or different material from that of the upper head body, but at least one of the lower head body and the upper head body is made of the second density material. 
     If the head body consists of an upper head body and a lower head body which are fitted with each other and a density of the lower head body is different from that of the upper head body, there are three situations are further illustrated as below. 
     First, if the upper head body is made of a first density material, the lower head body is made of a second density material, a density of the first density material is larger than that of the second density material. 
     A stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body and intercommunicated with each other, the head body is separated and includes an upper head body and a lower head body, which are mutually fitted with each other. 
     The sound collecting surface includes an upper sound collecting surface disposed on the upper head body and a lower sound collecting surface disposed on the lower head body, the upper sound collecting surface is communicated with the lower sound collecting surface through the sound guiding pore, the sound guiding pore intersects with and communicates with the lateral sound guiding aperture. 
     A tubular rivet is disposed at and fitted with one end of the sound guiding pore of the lower head body by an interference fit, a tolerance fit or a screw thread fit. A rod chamber of the tubular rivet runs through two ends of the tubular rive along an axis of the tubular rivet. A cap portion surface of the tubular rivet is shape-matching with one end surface of the lower head body. The end of the rod portion of the tubular rivet abuts against the lateral sound guiding aperture. 
     A profiled tubular rivet is disposed at and is fitted with the other end of the sound guiding pore in the lower head body by an interference fit, a tolerance fit or a screw thread fit. An outside surface of a head portion of the profiled tubular rivet is shape-matching with the lower collecting surface of the lower head body. A rod chamber of the tubular rivet runs through two ends of the tubular rivet along an axis of the tubular rivet. An end of the rod portion of the profiled tubular rivet abuts against the lateral sound guiding aperture. 
     A stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body and intercommunicated with each other, the head body is separated and includes an upper head body and a lower head body, which are mutually fitted with each other. 
     The sound collecting surface includes an upper sound collecting surface disposed on the upper head body and a lower sound collecting surface disposed on the lower head body, the upper sound collecting surface is communicated with the lower sound collecting surface through the sound guiding pore, the sound guiding pore intersects with and communicates with the lateral sound guiding aperture. 
     A tubular rivet is disposed at and fitted with one end of the sound guiding pore of the lower head body by an interference fit, a tolerance fit or a screw thread fit. A rod chamber of the tubular rivet runs through two ends of the tubular rive along an axis of the tubular rivet. A cap portion surface of the tubular rivet is shape-matching with and closely fitted with one end surface of the lower head body. A hole is formed in a rod portion of the tubular rivet and runs through the two side tube walls of the rod portion, an axis of the hole overlaps with that of the lateral sound guiding aperture, and an aperture of the hole is the same as that of the that of the lateral sound guiding aperture. 
     A profiled tubular rivet is disposed at and fitted with the other end of the sound guiding pore of the lower head body by an interference fit, a tolerance fit or a screw thread fit. An outside surface of a head portion of the profiled tubular rivet is shape-matching with the lower sound collecting surface of the lower head body. A rod chamber of the profiled tubular rivet runs through two ends of the profiled tubular rivet along an axis thereof. An end of the rod portion of the profiled tubular rivet abuts against the tubular rivet. 
     A stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body and intercommunicated with each other, the head body is separated and includes an upper head body and a lower head body, which are mutually fitted with each other. 
     The sound collecting surface includes an upper sound collecting surface disposed on the upper head body and a lower sound collecting surface disposed on the lower head body, the upper sound collecting surface is communicated with the lower sound collecting surface through the sound guiding pore, the sound guiding pore intersects with and communicates with the lateral sound guiding aperture. 
     A tubular rivet is disposed at and fitted with one end of the sound guiding pore of the lower head body by an interference fit, a tolerance fit or a screw thread fit. A rod chamber of the tubular rivet runs through two ends of the tubular rive along an axis of the tubular rivet. A cap portion surface of the tubular rivet is shape-matching with and closely fitted with one end surface of the lower head body. 
     A profiled tubular rivet is disposed at and fitted with the other end of the sound guiding pore of the lower head body by an interference fit, a tolerance fit or a screw thread fit. An outside surface of a head portion of the profiled tubular rivet is shape-matching with the lower sound collecting surface of the lower head body. A rod chamber of the profiled tubular rivet runs through two ends of the profiled tubular rivet along an axis thereof. A hole is formed in a rod portion of the profiled tubular rivet and runs through the two side tube walls of the rod portion, an axis of the hole overlaps with that of the lateral sound guiding aperture, and an aperture of the hole is the same as that of the that of the lateral sound guiding aperture. A rod portion of the profiled tubular rivet abuts against the rod portion of the tubular rivet. 
     A stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body and intercommunicated with each other, the head body is separated and includes an upper head body and a lower head body, which are mutually fitted with each other. 
     A hollow tube is disposed in and fitted with the sound guiding pore of the lower head body. 
     A tubular rivet is disposed at and fitted with one end of the sound guiding pore of the lower head body by an interference fit, a tolerance fit or a screw thread fit. A rod chamber of the tubular rivet runs through two ends of the tubular rive along an axis thereof. A cap portion surface of the tubular rivet is shape-matching with and closely fitted with one end surface of the lower head body. An end of the rod portion of the tubular rivet abuts against one end of the hollow tube. 
     A profiled tubular rivet is disposed at and fitted with the other end of the sound guiding pore of the lower head body by an interference fit, a tolerance fit or a screw thread fit. An outside surface of a head portion of the profiled tubular rivet is shape-matching with the lower sound collecting surface of the lower head body. A rod chamber of the profiled tubular rivet runs through two ends of the profiled tubular rivet along an axis thereof. An end of the rod portion of the profiled tubular rivet abuts against the other end of the hollow tube. 
     The lateral sound guiding aperture is communicated with a tube chamber of the hollow tube, a rod chamber of the tubular rivet, a rod chamber of the profiled tubular rivet. 
     Further, a hole is formed in the hollow tube, communicated with the side guiding hole and runs through at least one side tube wall of the lateral sound guiding aperture. 
     A stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body and intercommunicated with each other, the head body is separated and includes an upper head body and a lower head body, which are mutually fitted with each other. 
     A hollow tube is disposed in and fitted with the sound guiding pore of the lower head body. 
     A tubular rivet is disposed at and fitted with one end of the sound guiding pore of the lower head body by an interference fit, a tolerance fit or a screw thread fit. A rod chamber of the tubular rivet runs through two ends of the tubular rive along an axis thereof. A cap portion surface of the tubular rivet is shape-matching with and closely fitted with one end surface of the lower head body. An end of the rod portion of the tubular rivet abuts against one end of the hollow tube. 
     A profiled tubular rivet is disposed at and fitted with the other end of the sound guiding pore of the lower head body by an interference fit, a tolerance fit or a screw thread fit. An outside surface of a head portion of the profiled tubular rivet is shape-matching with the lower sound collecting surface of the lower head body. A rod chamber of the profiled tubular rivet runs through two ends of the profiled tubular rivet along an axis thereof. An end of the rod portion of the profiled tubular rivet abuts against the other end of the hollow tube. 
     The lateral sound guiding aperture is communicated with a tube chamber of the hollow tube, a rod chamber of the tubular rivet, a rod chamber of the profiled tubular rivet. 
     Further, a hole is formed in a rod portion of the semi-tubular, the hole communicates with the lateral sound guiding aperture and runs through at least one side tube wall of the lateral sound guiding aperture. 
     A stethoscope head, where the stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body, the stethoscope head is separated and includes an upper head body and a lower head body which are mutually fitted with each other. 
     A hollow tube is disposed in and fitted with the sound guiding pore of the lower head body. 
     A tubular rivet is disposed at and fitted with one end of the sound guiding pore of the lower head body by an interference fit, a tolerance fit or a screw thread fit. A rod chamber of the tubular rivet runs through two ends of the tubular rive along an axis thereof. A cap portion surface of the tubular rivet is shape-matching with and closely fitted with one end surface of the lower head body. An end of the rod portion of the tubular rivet abuts against one end of the hollow tube. 
     A profiled tubular rivet is disposed at and fitted with the other end of the sound guiding pore of the lower head body by an interference fit, a tolerance fit or a screw thread fit. An outside surface of a head portion of the profiled tubular rivet is shape-matching with the lower sound collecting surface of the lower head body. A rod chamber of the profiled tubular rivet runs through two ends of the profiled tubular rivet along an axis thereof. An end of the rod portion of the profiled tubular rivet abuts against the other end of the hollow tube. 
     The lateral sound guiding aperture is communicated with a tube chamber of the hollow tube, a rod chamber of the tubular rivet, a rod chamber of the profiled tubular rivet. 
     Further, a hole is formed in the profiled tubular rivet and runs through at least one side tube wall of the lateral sound guiding aperture, an axis of the hole overlaps with that of the lateral sound guiding aperture, and an aperture of the hole is the same as that of the that of the lateral sound guiding aperture 
     Second, if the lower head body is made of a first density material, the upper head body is made of a second density material, a density of the first density material is larger than that of the second density material. 
     A stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body, the head body is separated and includes an upper head body and a lower head body, which are mutually fitted with each other. 
     The sound collecting surface includes an upper sound collecting surface disposed on the upper head body and a lower sound collecting surface disposed on the lower head body, the upper sound collecting surface is communicated with the lower sound collecting surface through the sound guiding pore, the sound guiding pore intersects with and communicates with the lateral sound guiding aperture. 
     A profiled tubular rivet is disposed at and fitted with one end of the sound guiding pore of the upper head body by an interference fit, a tolerance fit or a screw thread fit. An outside surface of a head portion of the profiled tubular rivet is shape-matching with the upper sound collecting surface of the upper head body. A rod chamber of the profiled tubular rivet runs through two ends of the profiled tubular rivet along an axis thereof. The other end of the sound guiding pore in the upper head body is provided with an internal thread which is fitted with the lower head body. An outside surface of one end of the lower head body is provided with an external thread which is fitted with the internal thread. 
     Third, if both of the lower head body and the upper head body are made of the second density material. 
     A stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body, the head body is separated and includes an upper head body and a lower head body, which are mutually fitted with each other. 
     The sound collecting surface includes an upper sound collecting surface disposed on the upper head body and a lower sound collecting surface disposed on the lower head body, the upper sound collecting surface is communicated with the lower sound collecting surface through the sound guiding pore, the sound guiding pore intersects with and communicates with the lateral sound guiding aperture. 
     A first profiled tubular rivet is disposed at and fitted with the one end of the sound guiding pore of the upper head body by an interference fit, a tolerance fit or a screw thread fit. An outside surface of a head portion of the first profiled tubular rivet is shape-matching with the upper sound collecting surface of the upper head body. A rod chamber of the first profiled tubular rivet runs through two ends of the first profiled tubular rivet along an axis thereof. The other end of the sound guiding pore of the upper head body is provided with an internal thread which is fitted with the lower head body. 
     A tubular rivet is disposed at and fitted with one end of the sound guiding pore of the lower head body by an interference fit. A rod chamber of the tubular rivet runs through two ends of the tubular rive along an axis thereof. A cap portion surface of the tubular rivet is shape-matching with and closely fitted with one end surface of the lower head body. An end of the rod portion of the tubular rivet abuts against the lateral sound guiding aperture. 
     A second profiled tubular rivet is disposed at and fitted with the other end of the sound guiding pore of the lower head body by an interference fit. An outside surface of a head portion of the second profiled tubular rivet is shape-matching with the lower sound collecting surface. A chamber in the rod portion of the second profiled tubular rivet runs through both ends of the second profiled tubular rivet along an axis thereof. An end of the rod portion of the second profiled tubular rivet abuts against the lateral sound guiding aperture. 
     An outside surface of one end of the lower head body is provided with an external thread which is fitted with the internal thread. 
     A stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body, the head body is separated and includes an upper head body and a lower head body, which are mutually fitted with each other. 
     The sound collecting surface includes an upper sound collecting surface disposed on the upper head body and a lower sound collecting surface disposed on the lower head body, the upper sound collecting surface is communicated with the lower sound collecting surface through the sound guiding pore, the sound guiding pore intersects with and communicates with the lateral sound guiding aperture. 
     A first profiled tubular rivet is disposed at and fitted with the one end of the sound guiding pore of the upper head body by an interference fit, a tolerance fit or a screw thread fit. An outside surface of a head portion of the first profiled tubular rivet is shape-matching with the upper sound collecting surface of the upper head body. A rod chamber of the first profiled tubular rivet runs through two ends of the first profiled tubular rivet along an axis thereof. The other end of the sound guiding pore of the upper head body is provided with an internal thread which is fitted with the lower head body. 
     A tubular rivet is disposed at and fitted with one end of the sound guiding pore of the lower head body by an interference fit, a tolerance fit or a screw thread fit, a rod chamber of the tubular rivet runs through two ends of the tubular rive along an axis thereof, a cap portion surface of the tubular rivet is shape-matching with and closely fitted with one end surface of the lower head body; a hole is formed in the rod portion of the tubular rivet, the hole runs through the two side tube walls of the rod portion, an axis of the hole overlaps with that of the lateral sound guiding aperture, and an aperture of the hole is the same as that of the that of the lateral sound guiding aperture. 
     A second profiled tubular rivet is disposed at and fitted with the other end of the sound guiding pore of the lower head body by an interference fit, an outside surface of a head portion of the second profiled tubular rivet is shape-matching with the lower sound collecting surface, a chamber in the rod portion of the second profiled tubular rivet runs through both ends of the second profiled tubular rivet along an axis thereof, an end of the rod portion of the second profiled tubular rivet abuts against that of the tubular rivet. 
     An outside surface of one end of the lower head body is provided with an external thread which is fitted with the internal thread. 
     A stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body, the head body is separated and includes an upper head body and a lower head body, which are mutually fitted with each other. 
     The sound collecting surface includes an upper sound collecting surface disposed on the upper head body and a lower sound collecting surface disposed on the lower head body, the upper sound collecting surface is communicated with the lower sound collecting surface through the sound guiding pore, the sound guiding pore intersects with and communicates with the lateral sound guiding aperture. 
     A first profiled tubular rivet is disposed at and fitted with the one end of the sound guiding pore of the upper head body by an interference fit, a tolerance fit or a screw thread fit. An outside surface of a head portion of the first profiled tubular rivet is shape-matching with the upper sound collecting surface of the upper head body. A rod chamber of the first profiled tubular rivet runs through two ends of the first profiled tubular rivet along an axis thereof. The other end of the sound guiding pore of the upper head body is provided with an internal thread which is fitted with the lower head body. 
     A tubular rivet is disposed at and fitted with one end of the sound guiding pore of the lower head body by an interference fit. A rod chamber of the tubular rivet runs through two ends of the tubular rive along an axis thereof. A cap portion surface of the tubular rivet is shape-matching with and closely fitted with one end surface of the lower head body. A second profiled tubular rivet is disposed at and fitted with the other end of the sound guiding pore of the lower head body by an interference fit. An outside surface of a head portion of the second profiled tubular rivet is shape-matching with the lower sound collecting surface. A chamber in the rod portion of the second profiled tubular rivet runs through both ends of the second profiled tubular rivet along an axis thereof. A rod portion of the second profiled tubular rivet abuts against that of the lateral sound guiding aperture. 
     An outside surface of one end of the lower head body is provided with an external thread which is fitted with the internal thread. 
     Where, the sound collecting surface may be a curved surface, a conical surface or a combination thereof. 
     If the head body is integrated: 
     A stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body and intercommunicated with each other; the head body is integrated and made of a second density material, the sound collecting surface may include only one sound collecting surface, a sound guiding layer is the same as the sound collecting surface in shape and includes a hole which runs through a bottom thereof and is communicated with the sound guiding pore, the sound guiding layer consists of a profiled tubular rivet, a density of the profiled tubular rivet is larger than that of the second density material. 
     Further, an outside surface of the profiled tubular rivet is shape-matching with and closely fitted with the sound collecting surface of the head body, an outside surface of a rod portion of the profiled tubular rivet is closely fitted with the sound guiding pore. A rod portion of the profiled tubular rivet is fitted with the sound guiding pore by an interference fit, a tolerance fit or a screw thread fit. 
     Further, a rod chamber of the profiled tubular rivet is communicated with the lateral sound guiding aperture. 
     Further, the sound collecting surface may include an upper sound collecting surface and a lower sound collecting surface; the profiled tubular rivet includes a first profiled tubular rivet and a third profiled tubular rivet. 
     A rod chamber of the first profiled tubular rivet runs through two ends of the first profiled tubular rivet. A rod chamber of the third profiled tubular rivet runs through two ends of the third profiled tubular rivet. 
     An outside surface of a head portion of the first profiled tubular rivet is shape-matching with and closely fitted with the upper sound collecting surface, an outside surface of a rod portion of the first profiled tubular rivet is closely fitted with the sound guiding pore, a rod chamber of the first profiled tubular rivet is communicated with the lateral sound guiding aperture. 
     An outside surface of a head portion of the third profiled tubular rivet is shape-matching with and closely fitted with the upper sound collecting surface, an outside surface of a rod portion of the third profiled tubular rivet is closely fitted with the sound guiding pore, a rod chamber of the third profiled tubular rivet is communicated with the lateral sound guiding aperture. 
     Further, the sound collecting surface may include an upper sound collecting surface and a lower sound collecting surface; the profiled tubular rivet includes a first profiled tubular rivet and a third profiled tubular rivet. 
     A rod chamber of the first profiled tubular rivet runs through two ends of the first profiled tubular rivet. A rod chamber of the third profiled tubular rivet runs through two ends of the third profiled tubular rivet. 
     An outside surface of a head portion of the first profiled tubular rivet is shape-matching with and closely fitted with the upper sound collecting surface, an outside surface of a rod portion of the first profiled tubular rivet is closely fitted with the sound guiding pore. A rod portion of the first profiled tubular rivet is fitted with the sound guiding pore by an interference fit, a tolerance fit or a screw thread fit. A rod chamber of the first profiled tubular rivet is communicated with the lateral sound guiding aperture. 
     An outside surface of a head portion of the third profiled tubular rivet is shape-matching with and closely fitted with the upper sound collecting surface, an outside surface of a rod portion of the third profiled tubular rivet is closely fitted with the sound guiding pore. A rod portion of the profiled tubular rivet is fitted with the sound guiding pore by an interference fit, a tolerance fit or a screw thread fit. A rod portion of the third profiled tubular rivet is fitted with the sound guiding pore by an interference fit, a tolerance fit or a screw thread fit, a rod chamber of the third profiled tubular rivet is communicated with the lateral sound guiding aperture. An end of the rod portion of the first profiled tubular rivet abuts against the third profiled tubular rivet. 
     A hole is formed in the rod portion of the first profiled tubular rivet or the third profiled tubular rivet, the hole is communicated with a rotation shaft and the rod chamber and runs through at least one side rod wall of the rod portion. 
     Further, the sound collecting surface may include an upper sound collecting surface and a lower sound collecting surface; the profiled tubular rivet includes a first profiled tubular rivet and a third profiled tubular rivet. 
     A rod chamber of the first profiled tubular rivet runs through two ends of the first profiled tubular rivet. A rod chamber of the third profiled tubular rivet runs through two ends of the third profiled tubular rivet. 
     An outside surface of a head portion of the first profiled tubular rivet is shape-matching with and closely fitted with the upper sound collecting surface, an outside surface of a rod portion of the first profiled tubular rivet is closely fitted with the sound guiding pore, a rod chamber of the first profiled tubular rivet is communicated with the lateral sound guiding aperture. 
     An outside surface of a head portion of the third profiled tubular rivet is shape-matching with and closely fitted with the upper sound collecting surface, an outside surface of a rod portion of the third profiled tubular rivet is closely fitted with the sound guiding pore, a rod chamber of the third profiled tubular rivet is communicated with the lateral sound guiding aperture. 
     A sound guiding layer on an inner wall of the sound guiding pore is a hollow tube. An outer wall of the hollow tube is closely fitted with the inner wall of the sound guiding pore. The hollow tube is fitted with the sound guiding pore by an interference fit, a tolerance fit or a screw thread fit. Two ends of the hollow tube abuts against an end of the rod portion of the first profiled tubular rivet and an end of the rod portion of the third profiled tubular rivet respectively. 
     A hole is formed in the hollow tube, the hole is communicated with the lateral sound guiding aperture and the rod chamber and runs through at least one side rod wall of the rod portion. 
     A stethoscope head includes a head body and a sound guiding conduit formed in the head body, the sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body; the head body is integrated and made of a second density material, the sound guiding layer is composed of a profiled tubular rivet, a density of the profiled tubular rivet is larger than that of the second density material. 
     Further, an outside surface of a head portion of the profiled tubular rivet is shape-matching with and closely fitted with the sound collecting surface of the head body, a rod portion of the profiled tubular rivet is fitted with the sound guiding pore by an interference fit, a tolerance fit or a screw thread fit, an outside surface of a rod portion of the profiled tubular rivet is closely fitted with the sound guiding pore. 
     Further, a rod chamber of the profiled tubular rivet is communicated with the lateral sound guiding aperture. 
     Further, a sound guiding layer on an inner wall of the sound guiding pore may be a hollow tube. An outer wall of the hollow tube is fitted with the inner wall of the sound guiding pore in a non-ratable and immovable manner. Two ends of the hollow tube abut against rod ends of the profiled tubular rivet. A hole is formed in the hollow tube, an axis of the hole overlaps with that of the lateral sound guiding aperture, an aperture of the hole is the same as that of the that of the lateral sound guiding aperture, the hole runs through at least one side rod wall of the rod portion and is communicated with the rod chamber. 
     The present disclosure can be implemented in the following ways. 
     A method for reducing a weight of a stethoscope head, where the stethoscope head includes a head body and a sound guiding conduit formed in the head body, the which sound guiding conduit includes a sound collecting surface, a sound guiding pore and a lateral sound guiding aperture, all of which are located on the head body, a first density material is provided, at least the sound guiding layer on the sound collecting surface is made of the first density material so as to ensure a sound conducting quality of the stethoscope head; a second density material is provided, at least a portion of the stethoscope head is made of the second density material, a density of the second density material is less than that of the first density material. 
     Further, a sound guiding layer in the sound guiding pore is made of a third density material, the density of the second density material is less than that of the third density material, a density of the third density material is the same as or different from that of the first density material. 
     The densities of the various materials are as follows: such as copper (with a density of 8.9 g/cm 3 ), titanium alloy (with a density of 7.82 g/cm 3 ), stainless steel, steel (with a density of 7.8 g/cm 3 ), zinc alloy (with a density of 6.58 g/cm 3 ) or aluminium alloy (with a density of 2.7 g/cm 3 ), engineering plastics (with a density of in a range of 0.8 g/cm 3  to 2 g/cm 3 ) and engineering rubber (with a density of in a range of 0.4 g/cm 3  to 1.5 g/cm 3 ) 
     The present disclosure possesses the following benefits. 
     First, the head body is made of a low density material, thereby reducing a weight of the head body per se, second, the sound is reflected by the sound guiding layer during conducting of the sound and the sound guiding layer is made of a higher density material, therefore the conduction and magnification of the sound are improved, the hearing effect does not been affected, the present further possesses the following benefits. 
     First, a consumption of the high density material is reduced by 50%, the cost of the material is significantly reduced. 
     Second, a machining of the high density material is reduced by 40%, thereby reducing consumed cutting tools and machining time required for machining the high density material, the cost for machining is significantly reduced, for example, a machining manner in which the high density material is enclosed by the low density material by an injection is high in efficiency and low in cost. 
     Third, a weight of the head body is reduced to 60%, thereby the product is portable. 
     Fourth, a color of the stethoscope head are enriched, thereby providing various color match, for example, the two different densities materials may select from different colors. 
     The upper head body and lower head body are formed by casting because the head body is separated, thereby greatly reducing the processing difficulty for vehicle processing in the prior art and a cost for working. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram the present disclosure (with one sound collecting surface); 
         FIG. 2  is a schematic diagram showing an assembly of the present disclosure (where only a lower head body is made of a low-density material); 
         FIG. 3  is a schematic diagram showing the present disclosure (where only a lower head body is made of a low-density material); 
         FIG. 4  is a schematic diagram showing an upper head body of the present disclosure; 
         FIG. 5  is a schematic diagram showing a tubular rivet of the present disclosure; 
         FIG. 6  is a schematic diagram showing a profiled tubular rivet of the present disclosure; 
         FIG. 7  is a schematic diagram showing a lower head body of the present disclosure; 
         FIG. 8  is a schematic diagram showing an assembly of the present disclosure (where only an upper head body is made of a low-density material); 
         FIG. 9  is a schematic diagram showing an assembly of the present disclosure (where only an upper head body is made of a low-density material); 
         FIG. 10  is a schematic diagram showing a profiled tubular rivet of the present disclosure; 
         FIG. 11  is a schematic diagram showing an assembly of the present disclosure (where both of an upper head body and a lower head are made of low-density material); 
         FIG. 12  is a schematic diagram of the present disclosure (where both of an upper head body and a lower head are made of low-density material); 
         FIG. 13  is a schematic diagram of the present disclosure (where a head body is integrated). 
         FIG. 14  is a schematic diagram of the present disclosure (where a head body is integrated). 
         FIG. 15  is a schematic diagram of the present disclosure (where a head body is integrated). 
         FIG. 16  is a schematic diagram of the present disclosure (where a head body is integrated). 
         FIG. 17  is a schematic diagram of the present disclosure (where a head body is integrated). 
         FIG. 18  is a schematic diagram showing a hollow tube of the present disclosure. 
     
    
    
     Where in the drawings:
       1 : upper head body;  11 : internal thread;  12 : upper sound collecting surface;  2 : lower head body;  21 : end surface;  22 : external thread;  23 : lower sound collecting surface;  3 : tubular rivet;  31 : chamber in a rod portion;  32 : cap portion of the tubular rivet;  33 : end of the rod portion of the tubular rivet;  34 : hole;  35 : rod portion;  4 : lateral sound guiding aperture; D: sound guiding pore;  5 : first profiled tubular rivet;  51 : outside surface of a head portion;  52 : chamber in a rod portion;  53 : end of the rod portion;  54 : hole;  55 : rod portion;  5 A: profiled tubular rivet;  51 A: outside surface of a head portion;  52 A: chamber in a rod portion;  53 A: end of a rod portion of a first profiled tubular rivet;  54 A: hole;  55 A: rod portion;  57 A: nailhead;  6 : second profiled tubular rivet  61 : outside surface of a head portion;  62 : chamber in the rod portion;  63 : rod portion;  7 : third profiled tubular rivet;  71 : outside surface of a head portion;  72 : chamber in the rod portion;  73 : rod portion;  74 : end of the rod portion;  8 : head body;  9 : hollow tube;  91 : tube chamber;  92 : inner wall  93 : hole;  93 A: hollow tube;  92 A: inner wall;  93 A: hole.   

     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In order to illustrate the present disclosure and the beneficial effects thereof in detail, the present disclosure will be further illustrated below with reference to the accompanying drawings, and the protection scope of the present disclosure is not limited to the contents of the specific embodiments. 
     The present disclosure is further illustrated with reference to the drawings. 
     In a first embodiment, the present disclosure is further illustrated below with reference to  FIG. 1 . 
     A stethoscope head includes a head body and a sound guiding conduit in the head body. The sound guiding conduit includes a lower sound collecting surface  23 , a sound guiding pore D and a lateral sound guiding aperture  4 . The lower sound collecting surface  23 , the sound guiding pore D and the lateral sound guiding aperture  4  are provided in a lower head body  2 . 
     In the present embodiment, there exists only one sound collecting surface, i.e. the lower sound collecting surface  23  in the present embodiment. A sound guiding layer is closely fitted on the lower sound collecting surface  23 . The sound guiding layer may be a first profiled tubular rivet  5 , an outside surface  51  of a head portion of the first profiled tubular rivet  5  fits the lower sound collecting surface  23  and closely matches with the lower sound collecting surface  23 , and an outer surface of a rod portion  55  of the first profiled tubular rivet  5  closely matches with the sound guiding pore D. 
     A chamber  52  in the rod portion of the first profiled tubular rivet  5  runs through both ends of the first profiled tubular rivet  5 . The chamber  52  is communicated with the lateral sound guiding aperture  4 . 
     The rod portion  55  of the first profiled tubular rivet  5  includes a hole  54  which opens at a side wall of the rod portion  55  and is communicated with the chamber  52 . The hole  54  is communicated with the lateral sound guiding aperture  4 . 
     During machining, the lower head body  2  is formed by casing, subsequently the sound guiding pore D and the lateral sound guiding aperture  4  are formed in the lower head body  2 , and then the rod portion  55  of the first profiled tubular rivet  5  is disposed in the sound guiding pore D. 
     Alternatively, the first profiled tubular rivet  5  is prepared, then the rod portion  55  and the outer end surface  51  of the first profiled tubular rivet  5  are covered by the lower head body  2  in a non-rotatable and immovable manner by injection moulding, thereby forming an integrated structure where the first profiled tubular rivet  5  is closely fitted with the lower head body  2 . 
     In a second embodiment, the present disclosure is further illustrated with reference to  FIG. 17  and  FIG. 18 . 
     A stethoscope head includes a head body and a sound guiding conduit in the head body. The sound guiding conduit includes a lower sound collecting surface  23 , a sound guiding pore D and a lateral sound guiding aperture  4 . The lower sound collecting surface  23 , the sound guiding pore D and the lateral sound guiding aperture  4  are provided in a lower head body  2 . 
     A sound guiding layer is closely fitted on the lower sound collecting surface  23 . The sound guiding layer may be a first profiled tubular rivet  5 , an outside surface  51  of a head portion of the first profiled tubular rivet  5  fits the lower sound collecting surface  23  and closely matches with the lower sound collecting surface  23 , and an outer surface of a rod portion  55  of the first profiled tubular rivet  5  closely matches with the sound guiding pore D. 
     A chamber  52  in the rod portion of the first profiled tubular rivet  5  runs through both ends of the first profiled tubular rivet  5 . The chamber  52  is communicated with the lateral sound guiding aperture  4 . 
     Further, a sound guiding layer made of aluminium alloy, which may be a hollow tube  9 A with one blind end, is disposed on an inner wall of the sound guiding pore D. An outer wall of the hollow tube is closely fitted with an inner wall of the sound guiding pore D by means of tolerance fit, thread fit and so on. 
     An end  53  of the rod portion of the first profiled tubular rivet  5  is adjacent to but not in contact with an open end of the hollow tube  9 A, alternatively, the end  53  of the rod portion of the first profiled tubular rivet  5  abuts against the open end of the hollow tube  9 A. 
     The first profiled tubular rivet  5  and the hollow tube  9 A may be made of steel especially stainless steel, copper, aluminium alloy or the like, and the lower head body  2  may be made of engineering plastics, engineering rubber or the like. 
     In a third embodiment, the present disclosure is further illustrated with reference to  FIG. 2 ,  FIG. 3 ,  FIG. 4 ,  FIG. 5 ,  FIG. 6  and  FIG. 7 . 
     A stethoscope head consists of individual upper head body  1  and lower head body  2 , an upper sound collecting surface  12  located on the upper head body  1 , a lower sound collecting surface  23  which is located on the lower head body  2  and is opposite to the upper sound collecting surface  12 , a lateral sound guiding aperture  4  in the lower head body  2 , a tubular rivet  3  and a first profiled tubular rivet  5 . 
     The upper head body  1  is provided with an internal thread  11 , and the lower head body  2  is provided with an external thread  22 , so that the upper head body  1  and the lower head body  2  are fixed together through the cooperation between the internal thread  11  and the external thread  22 . 
     A sound guiding pore D runs through the upper head body  1  and the lower head body  2 , so that the upper sound collecting surface  12  is communicated with the lower sound collecting surface  23  through the sound guiding pore D. The sound guiding pore D is communicated with and intersects with the lateral sound guiding aperture  4 . The upper head body  1  is made of stainless steel, and the lower head body  2  is made of engineering plastics. The tubular rivet  3  is disposed at one end of the sound guiding pore D in the lower head body  2  by an interference fit. A rod chamber  31  (i.e. a chamber in a rod portion) of the tubular rivet  3  runs through two ends of the tubular rivet  3  along an axis of the tubular rivet  3 . A cap portion  32  of the tubular rivet  3  is closely shape-fitted with an end surface  21  of the lower head body  2 . A rod portion of the tubular rivet  3  is closely fitted with the sound guiding pore D. An end  33  of the rod portion of the tubular rivet  3  abuts against the lateral sound guiding aperture  4 . The first profiled tubular rivet  5  is disposed at the other end of the sound guiding pore D in the lower head body  2  in interference fit. An outside surface  51  of a head portion of the first profiled tubular rivet  5  is matching with the lower sound collecting surface  23  of the lower head body  2 . A rod potion of the tubular rivet  5  is closely fitted with the sound guiding pore D. A rod chamber  52  of the first profiled tubular rivet  5  runs through two ends of the first profiled tubular rivet  5  along an axis thereof. An end  53  of the rod portion of the first profiled tubular rivet  5  abuts against the lateral sound guiding aperture  4 . 
     In a fourth embodiment, the present disclosure is further illustrated with reference to  FIG. 8 ,  FIG. 9  and  FIG. 10 . 
     A stethoscope head consists of an upper head body  1 , a lower head body  2 , an upper sound collecting surface  12  which is curved and located on the upper head body  1 , a lower sound collecting surface  23  which is located on the lower head body  2  and is opposite to the upper sound collecting surface  12 , a lateral sound guiding aperture  4  disposed in the lower head body  2  and a second profiled tubular rivet  6 . 
     The upper head body  1  is provided with an internal thread  11 , and the lower head body  2  is provided with an external thread  22 , so that the upper head body  1  and the lower head body  2  are fixed together through the cooperation between the internal thread  11  and the external thread  22 . 
     A sound guiding pore D runs through the upper head body  1  and the lower head body  2 , so that the upper sound collecting surface  12  is communicated with the lower sound collecting surface  23  through the sound guiding pore D. The sound guiding pore D is communicated with and intersects with the lateral sound guiding aperture  4 . 
     The upper head body  1  is made of engineering rubber, and the lower head body  2  is made of zinc alloy material. 
     A second profiled tubular rivet  6  is disposed at one end of the sound guiding pore D in the upper head body  1  by an interference fit. An outside surface  61  of a head portion of the second profiled tubular rivet  6  is shape-matching with the upper sound collecting surface  12  of the upper head body  1 . A chamber  62  in a rod portion  63  of the second profiled tubular rivet  6  runs through both ends of the second profiled tubular rivet  6 . The rod portion  63  is disposed in the sound guiding pore D, where an outside surface of the rod portion  63  is closely fitted with an inner wall of the sound guiding pore D. Another end of the sound guiding pore D in the upper head body  1  is provided with the internal thread  11  which is fitted with the lower head body  2 . 
     In a fifth embodiment, the present disclosure is further illustrated with reference to  FIG. 4 ,  FIG. 5 ,  FIG. 6 ,  FIG. 7 ,  FIG. 10 ,  FIG. 11  and  FIG. 12 . 
     A stethoscope head consists of an upper head body  1 , a lower head body  2 , an upper sound collecting surface  12  which located on the upper head body  1 , a lower sound collecting surface  23  which is located on the lower head body  2  and is opposite to the upper sound collecting surface  12 , a lateral sound guiding aperture  4  and a sound guiding pore D which are disposed in the lower head body  2 , a tubular rivet  3  and a first profiled tubular rivet  5 . 
     The upper head body  1  is provided with an internal thread  11 , and the lower head body  2  is provided with an external thread  22 , so that the upper head body  1  and the lower head body  2  are fixed together through the cooperation between the internal thread  11  and the external thread  22 . 
     The sound guiding pore D runs through the upper head body  1  and the lower head body  2 , so that the upper sound collecting surface  12  is communicated with the lower sound collecting surface  23  through the sound guiding pore D. The sound guiding pore D is communicated with and intersects with the lateral sound guiding aperture  4 . 
     In the case that both of the upper head body  1  and the lower head body  2  are made of engineering plastics or engineering rubber, the tubular rivet  3  and the first profiled tubular rivet  5  may be made of material such as copper (with a density of 8.9 g/cm 3 ), titanium alloy (with a density of 7.82 g/cm 3 ), stainless steel, steel (with a density of 7.8 g/cm 3 ), zinc alloy (with a density of 6.58 g/cm 3 ) or aluminium alloy (with a density of 2.7 g/cm 3 ), which has a density larger than that of engineering plastics or engineering rubber. 
     In the case that both of the upper head body  1  and the lower head body  2  are made of the aluminium alloy, the tubular rivet  3  and the first profiled tubular rivet  5  may be made of material such as copper (with a density of 8.9 g/cm 3 ), titanium alloy (with a density of 7.82 g/cm 3 ), steel (with a density of 7.8 g/cm 3 ), and zinc alloy (with a density of 6.58 g/cm 3 ), which has a density larger than that of the aluminium alloy. 
     The second profiled tubular rivet  6  is disposed at one end of the sound guiding pore D in the upper head body  1  by an interference fit. An outside surface  61  of a head portion of the second profiled tubular rivet  6  is matching with the upper sound collecting surface  12  on the upper head body  1 . A chamber  62  in the rod portion of the second profiled tubular rivet  6  runs through both ends of the second profiled tubular rivet  6 . The other end of the sound guiding pore D in the upper head body  1  is provided with the internal thread  11  which matches with the lower head body  2 . 
     The tubular rivet  3  is disposed at one end of the sound guiding pore D in the lower head body  2  by an interference fit. A rod chamber  31  of the tubular rivet  3  runs through two ends of the tubular rivet  3  along an axis of the tubular rivet  3 . A cap portion  32  of the tubular rivet  3  is closely fitted with an end surface  21  of the lower head body  2  and is shape-matching with the end surface  21  of the lower head body  2 . A rod portion  33  of the tubular rivet abuts against the lateral sound guiding aperture  4 . The first profiled tubular rivet  5  is disposed at the other end of the sound guiding pore D in the lower head body  2  by an interference fit. An outside surface  51  of a head portion of the first profiled tubular rivet  5  is shape-matching with the lower sound collecting surface  23  of the lower head body  2 , and a rod chamber  52  of the first profiled tubular rivet  5  runs through two ends of the first profiled tubular rivet  5  along an axis thereof. An end  53  of the rod portion of the first profiled tubular rivet  5  abuts against the lateral sound guiding aperture  4 . 
     In a sixth embodiment, the present disclosure is further illustrated with reference to  FIG. 13 ,  FIG. 14 ,  FIG. 15  and  FIG. 16 . 
     A stethoscope head includes a head body  8  and a sound guiding conduit formed in the head body. The sound guiding conduit includes a sound collecting surface, a sound guiding pore D and a lateral sound guiding aperture  4 . The sound collecting surface includes an upper sound collecting surface  12  and a lower sound collecting surface  23 . 
     The head body  8  is integral and made of engineering rubber. 
     A sound guiding layer on the upper sound collecting surface  12  is composed of a first profiled tubular rivet  5  made of copper. A sound guiding layer on the lower sound collecting surface  23  is composed of a third profiled tubular rivet  7  made of titanium alloy. 
     Further, an outside surface  51  of a head portion of the first profiled tubular rivet  5  is shape-matching with and closely fitted with the upper sound collecting surface  12  of the head body  8 . An outside surface of a rod portion of the first profiled tubular rivet  5  is closely fitted with the sound guiding pore D. 
     An outside surface  71  of a head portion of the third profiled tubular rivet  7  is shape-matching with and closely fitted with the lower sound collecting surface  23  of the head body  8 . An outside surface of a rod portion  73  of the third profiled tubular rivet  7  is closely fitted with the sound guiding pore D. 
     Further, a rod chamber  52  of the first profiled tubular rivet  5  runs through two ends of the first profiled tubular rivet  5  and is communicated with the lateral sound guiding aperture  4 . A rod chamber  72  of the third profiled tubular rivet  7  runs through two ends of the third profiled tubular rivet  7  and is communicated with the lateral sound guiding aperture  4 . 
     Referring to  FIG. 13  and  FIG. 14 , an end of the rod portion of the first profiled tubular rivet  5  abuts against and is communicated with the lateral sound guiding aperture  4 . An end of the rod portion of the third profiled tubular rivet  7  abuts against and is communicated with the lateral sound guiding aperture  4 . 
     Further referring to  FIG. 15 , a through hole, which is coaxial with the lateral sound guiding aperture  4  and has a bore diameter same as that of the lateral sound guiding aperture  4 , is formed in the rod portion  73  of the third profiled tubular rivet  7  and opens on the wall of the rod portion  73 , and is communicated with the rod chamber. An end of the rod portion of the first profiled tubular rivet  5  abuts against that of the third profiled tubular rivet  7 . 
     Alternatively, referring to  FIG. 16 , a through hole, which is coaxial with the lateral sound guiding aperture  4  and has a bore diameter same as that of the lateral sound guiding aperture  4 , is formed in the rod portion  55  of the first profiled tubular rivet  5  and opens on the wall of the rod portion  55 , and is communicated with the rod chamber  52 . An end of the rod portion of the third profiled tubular rivet  7  abuts against that of the first profiled tubular rivet  5 . 
     In a seventh embodiment, the present disclosure is further illustrated with reference to  FIG. 13 ,  FIG. 14 ,  FIG. 15  and  FIG. 16 . 
     The present embodiment of the present invention provides a method for manufacturing a stethoscope head with a reduced weight, and the stethoscope head includes a head body  8  and a sound guiding conduit formed in the head body. The sound guiding conduit includes an upper sound collecting surface  12 , a lower sound collecting surface  23 , a sound guiding pore D and a lateral sound guiding aperture  4 . 
     A first profiled tubular rivet  5  and a third profiled tubular rivet  7  are made of stainless steel. 
     The head body  8 , which may be assembled or integral, may be made of engineering plastics. 
     An outside surface  51  of a head portion of the first profiled tubular rivet  5  is shape-matching with and closely fitted with the upper sound collecting surface  12  of the head body  8 . An outside surface of a rod portion  55  of the first profiled tubular rivet  5  is closely fitted with the sound guiding pore D. 
     An outer surface  71  of a head portion of the third profiled tubular rivet  7  is shape-matching with and closely fitted with the lower sound collecting surface  23  of the head body  8 . An outside surface of a rod portion of the third profiled tubular rivet  7  is closely fitted with the sound guiding pore D. 
     In an eighth embodiment, the present disclosure is further illustrated with reference to  FIG. 9 . 
     The present embodiment of the present invention provides a method for manufacturing a stethoscope head with a reduced weight, and the stethoscope head includes an upper head body  1 , a lower head body  2  and a second profiled tubular rivet  6 . 
     The upper head body  1  is provided with a curved upper sound collecting surface  12 , and the lower head body  2  is provided with a lower sound collecting surface  23  and a lateral sound guiding aperture  4 , where the upper head body  1  is provided with an internal thread  11 , and the lower head body  2  is provided with an external thread  22 , so that the upper head body  1  and the lower head body  2  are fixed together through a fit of the internal thread  11  and the external thread  22 . 
     A sound guiding pore D runs through the upper head body  1  and the lower head body  2 , so that the upper sound collecting surface  12  is communicated with the lower sound collecting surface  23  through the sound guiding pore D. The sound guiding pore D is communicated with and intersects the lateral sound guiding aperture  4 . 
     The upper head body  1  is made of engineering rubber. 
     The lower head body  2  is made of stainless steel. 
     The second profiled tubular rivet  6  is made of aluminium alloy. 
     A second profiled tubular rivet  6  is disposed at one end of the sound guiding pore D in the upper head body  1  by an interference fit. An outside surface  61  of a head portion of the second profiled tubular rivet  6  is shape-matching with the upper sound collecting surface  12 , a chamber  62  in the rod portion of the second profiled tubular rivet  6  runs through both ends of the second profiled tubular rivet  6 , and the other end of the sound guiding pore D in the upper head body  1  is provided with the internal thread  11  fitted with the lower head body  2 . 
     Compared with the prior art, the present disclosure has benefits further illustrated below. 
     For example, an exemplary stethoscope in the prior art is manufactured by Wuxi Kaishun Medical Device Manufacturing CO., Ltd. 
     In the detection below, a sound collecting chamber refers to a chamber formed by fixing a diaphragm over the sound collecting surface of the head body. 
     A method for testing a sound conducting performance of the stethoscope includes steps as below. 
     First, the sound collecting chamber of the stethoscope head is placed on a sealing connector of a sound generator such that the sound collecting surface (i.e. the diaphragm) of the stethoscope head rightly faces a sound output port of the sound generator, and a joint between an outward face of the sound collecting surface and an inward face of the sound output port of the sound generator is in sealed status. A distance between the sound output port of the sound generator and the sound collecting surface of the stethoscope head is in a range from 8 mm to 10 mm. 
     Secondly, one end of a sound conducting tube with a diameter of 10 mm, a bore diameter of 4 mm and a length of 40 cm is connected to a sound conducting connector of the stethoscope head, and the other end of the sound conducting tube is connected to an audio receiver. 
     Thirdly, the sound generator and the audio receiver are turned on, a numerical value detected by the audio receiver is recorded and is divided by a standard numerical value of the sound generator to obtain a quotient, which is used for obtaining the sound conducting performance of the stethoscope. 
     A method for testing external noise resistance of the stethoscope includes steps as below. 
     First, a back surface of the sound collecting chamber of the stethoscope head is placed on the sealing connector of the sound generator such that the back surface of the sound collecting surface of the stethoscope head rightly faces the sound output port of the sound generator, and a joint between an outward face of the sound collecting surface and an inward face of the sound output port of the sound generator is in sealed status. The distance between the sound output port of the sound generator and the sound collecting surface of the stethoscope head is in a range from 4 mm to 6 mm. 
     Secondly, one end of the sound conducting tube with a diameter of 10 mm, an aperture of 4 mm and a length of 40 cm is connected to a sound conducting connector of the stethoscope head, and the other end of the sound conducting tube is connected to an audio receiver. 
     Thirdly, the sound generator and the audio receiver are turned on, a numerical value detected by the audio receiver is recorded and is divided by a standard numerical value of the sound generator to obtain a quotient, which is used for obtaining the external noise resistance of the stethoscope. 
     Comparing Example 1 
     from comparison of the stethoscope of the first embodiment of the present invention with stethoscopes of KS-410A, KS-410B and KS-410C types manufactured by Wuxi Kaishun Medical Device Manufacturing CO., Ltd, it can be known that time for manufacturing the inventive stethoscope is saved by about a quarter, a cost for manufacturing the inventive stethoscope is saved by more than one third, the external noise resistance of the inventive stethoscope is improved by about one fifth, and a weight of the inventive stethoscope is reduced by about one third, without significant change to the sound conducting performance, further, the inventive stethoscope is easy to carry and has a good appearance. 
     Comparative data of a stethoscope of the first embodiment of the present disclosure with the KS-410A type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with single sound 
                   
                   
                 comparison 
               
               
                 collecting surface 
                 The inventive stethoscope 
                 KS-410A 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Individually made of a 
                 Made of only high density 
                   
               
               
                   
                 combination of high density 
                 material 
               
               
                   
                 material and low density 
               
               
                   
                 material 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel (type 304) 
               
               
                 density material 
               
               
                 Material 
                 30 grams × CNY 0.035 
                 85 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 1.05 
                 per gram = CNY 2.97 
               
               
                 cost 
               
               
                 Name of low-density 
                 Polyformaldehyde (POM) 
               
               
                 material 
               
               
                 Material 
                 14 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.35 
               
               
                 cost 
               
               
                 Cutting tool 
                 CNY 1.85 
                 CNY 2.23 
               
               
                 consumption 
               
               
                 Machining time and 
                 258 sec × CNY 0.011 
                 341 sec × CNY 0.011 
                 Machining 
               
               
                 cost 
                 per second = CNY 2.86 
                 per second = CNY 3.75 
                 time is saved 
               
               
                   
                   
                   
                 by 24% 
               
               
                 Total cost 
                 CNY 6.11 
                 CNY 8.95 
                 Total cost is 
               
               
                   
                   
                   
                 save by 32% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 109 dB 
                 Measured value: 109.6 dB 
                 performance 
               
               
                 collected by a sound 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 has no 
               
               
                 collecting chamber 
                 500 HZ 
                 500 HZ 
                 significant 
               
               
                 of the stethoscope) 
                 Measured value: 102 dB 
                 Measured value: 101 dB 
                 change 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 35 dB 
                 Measured value: 42.6 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 500 HZ 
                 500 HZ 
                 18% to 21% 
               
               
                 of the stethoscope) 
                 Measured value: 28 dB 
                 Measured value: 35.3 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 44 grams 
                 85 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     Comparative data of a stethoscope of the first embodiment of the present disclosure with the KS-410B type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with single sound 
                   
                   
                 comparison 
               
               
                 collecting surface 
                 The inventive stethoscope 
                 KS-410B 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Individually made of a 
                 Made of only high density 
                   
               
               
                   
                 combination of high density 
                 material 
               
               
                   
                 material and low density 
               
               
                   
                 material 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 35 grams × CNY 0.035 
                 95 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 1.22 
                 per gram = CNY 3.32 
               
               
                 cost 
               
               
                 Name of low-density 
                 Polyformaldehyde (POM) 
               
               
                 material 
               
               
                 Material 
                 17 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.42 
               
               
                 cost 
               
               
                 Cutting tool 
                 CNY 1.65 
                 CNY 2.11 
               
               
                 consumption 
               
               
                 Machining time and 
                 276 second × CNY 0.011 
                 375 second × CNY 0.011 
                 Machining 
               
               
                 cost 
                 per second = CNY 3.03 
                 per second = CNY 4.12 
                 time is saved 
               
               
                   
                   
                   
                 by 26% 
               
               
                 Total cost 
                 CNY 6.32 
                 CNY 9.55 
                 Total cost is 
               
               
                   
                   
                   
                 save by 34% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 110 dB 
                 Measured value: 109.5 dB 
                 performance 
               
               
                 collected by a sound 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 500 HZ 
                 has no 
               
               
                 collecting chamber 
                 Measured value: 101 dB 
                 Measured value: 102.3 dB 
                 significant 
               
               
                 of the stethoscope) 
                   
                   
                 change 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 34 dB 
                 Measured value: 43 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source 114 dB 500 HZ 
                 Sound source 114 dB 500 HZ 
                 improved by 
               
               
                 collected by a back 
                 Measured value: 26.4 dB 
                 Measured value: 36.1 dB 
                 21% to 27% 
               
               
                 of the stethoscope) 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 52 grams 
                 95 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     Comparative data of a stethoscope of the first embodiment of the present disclosure with the KS-410C type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with single sound 
                   
                   
                 comparison 
               
               
                 collecting surface 
                 The inventive stethoscope 
                 KS-410C 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Individually made of a 
                 Made of only high density 
                   
               
               
                   
                 combination of high density 
                 material 
               
               
                   
                 material and low density 
               
               
                   
                 material 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 33 grams × CNY 0.035 
                 87 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 1.155 
                 per gram = CNY 3.045 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 18 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.45 
               
               
                 cost 
               
               
                 Cutting tool 
                 CNY 1.75 
                 CNY 2.08 
               
               
                 consumption 
               
               
                 Machining time 
                 278 second × CNY 0.011 
                 374 second × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 second = CNY 3.05 
                 per second = CNY 4.11 
                 time is saved 
               
               
                   
                   
                   
                 by 26% 
               
               
                 Total cost 
                 CNY 6.41 
                 CNY 9.23 
                 Total cost is 
               
               
                   
                   
                   
                 save by 31% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 107 dB 
                 Measured value: 108 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 500 HZ 
                 has no 
               
               
                 sound collecting 
                 Measured value: 101.2 dB 
                 Measured value: 102 dB 
                 significant 
               
               
                 chamber of the 
                   
                   
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 38 dB 
                 Measured value: 43.5 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 500 HZ 
                 improved by 
               
               
                 collected by a back 
                 Measured value: 27.3 dB 
                 Measured value: 36.1 dB 
                 13% to 25% 
               
               
                 of the stethoscope) 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 50 grams 
                 90 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     Comparing Example 2 
     from comparison of the stethoscope of the second embodiment of the present invention with stethoscopes of KS-450A, KS-450B and KS-450C types manufactured by Wuxi Kaishun Medical Device Manufacturing CO., Ltd, it can be known that time for manufacturing the inventive stethoscope is saved by about a quarter, a cost for manufacturing the inventive stethoscope is reduced by about one third, the external noise resistance of the inventive stethoscope is improved by about one fifth, a weight of the inventive stethoscope is reduced by about one third, without significant change to the sound conducting performance, further the inventive stethoscope is easy to carry and has a good appearance. 
     Comparative data of a stethoscope of the second embodiment of the present disclosure with the KS-450A type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with single sound 
                   
                   
                 comparison 
               
               
                 collecting surface 
                 The inventive stethoscope 
                 KS-450A 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Integrated combination of 
                 Made of only high density 
                   
               
               
                   
                 high density material and 
                 material 
               
               
                   
                 low density material formed 
               
               
                   
                 by injection molding 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 32 grams × CNY 0.035 
                 87 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 1.12 
                 per gram = CNY 3.04 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 19 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.48 
               
               
                 cost 
               
               
                 Cutting tool 
                 CNY 1.13 
                 CNY 2.24 
               
               
                 consumption 
               
               
                 Machining time 
                 212 second × CNY 0.011 
                 381 second × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 per second = CNY 2.33 
                 per second = CNY 4.19 
                 time is saved 
               
               
                   
                   
                   
                 by 26% 
               
               
                 Total cost 
                 CNY 5.6 
                 CNY 9.4 
                 Total cost is 
               
               
                   
                   
                   
                 save by 39% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 110 dB 
                 Measured value: 109.5 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 114 dB 
                 Sound source: 114 dB 500 HZ 
                 has no 
               
               
                 sound collecting 
                 500 HZ 
                 Measured value: 102.3 dB 
                 significant 
               
               
                 chamber of the 
                 Measured value: 101 dB 
                   
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 31.3 dB 
                 Measured value: 39.8 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 Measured value: 26.7 dB 
                 500 HZ 
                 21% to 28% 
               
               
                 of the stethoscope) 
                   
                 Measured value: 36.9 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 51 grams 
                 87 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     Comparative data of a stethoscope of the second embodiment of the present disclosure with the KS-450B type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with single sound 
                   
                   
                 comparison 
               
               
                 collecting surface 
                 The inventive stethoscope 
                 KS-450B 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Integrated combination of 
                 Made of only high density 
                   
               
               
                   
                 high density material and 
                 material 
               
               
                   
                 low density material formed 
               
               
                   
                 by injection molding 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 37 grams × CNY 0.035 
                 90 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 1.29 
                 per gram = CNY 3.15 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 17 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.42 
               
               
                 cost 
               
               
                 Cutting tool 
                 CNY 1.23 
                 CNY 2.30 
               
               
                 consumption 
               
               
                 Machining time 
                 225 sec × CNY 0.011 
                 390 sec × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 per sec = CNY 2.47 
                 per sec = CNY 4.29 
                 time is saved 
               
               
                   
                   
                   
                 by 43 
               
               
                 Total cost 
                 CNY 5.41 
                 CNY 9.74 
                 Total cost is 
               
               
                   
                   
                   
                 save by 45 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 111 dB 
                 Measured value: 108.5 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 has no 
               
               
                 sound collecting 
                 500 HZ 
                 500 HZ 
                 significant 
               
               
                 chamber of the 
                 Measured value: 103 dB 
                 Measured value: 101.6 dB 
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 32.2 dB 
                 Measured value: 38.1 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 500 HZ 
                 500 HZ 
                 16% to 22% 
               
               
                 of the stethoscope) 
                 Measured value: 29 dB 
                 Measured value: 37 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 53 grams 
                 88 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     Comparative data of a stethoscope of the second embodiment of the present disclosure with the KS-450C type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with single sound 
                   
                   
                 comparison 
               
               
                 collecting surface 
                 The inventive stethoscope 
                 KS-450C 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Integrated combination of 
                 Made of only high density 
                   
               
               
                   
                 high density material and 
                 material 
               
               
                   
                 low density material formed 
               
               
                   
                 by injection molding 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 33 grams × CNY 0.035 
                 85 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 1.15 
                 per gram = CNY 2.97 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 21 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.52 
               
               
                 cost 
               
               
                 Cutting tool 
                 CNY 1.07 
                 CNY 2.5 
               
               
                 consumption 
               
               
                 Machining time 
                 234 sec × CNY 0.011 
                 395 sec × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 per second = CNY 2.57 
                 per second = CNY 4.34 
                 time is saved 
               
               
                   
                   
                   
                 by 41 
               
               
                 Total cost 
                 CNY 5.31 
                 CNY 9.81 
                 Total cost is 
               
               
                   
                   
                   
                 save by 46 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 108.2 dB 
                 Measured value: 106 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 has no 
               
               
                 sound collecting 
                 500 HZ 
                 500 HZ 
                 significant 
               
               
                 chamber of the 
                 Measured value: 109.1 dB 
                 Measured value: 105.2 dB 
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 33.6 dB 
                 Measured value: 41.1 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 500 HZ 
                 500 HZ 
                 19% to 27% 
               
               
                 of the stethoscope) 
                 Measured value: 28.2 dB 
                 Measured value: 38.4 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 55 grams 
                 84 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     Comparing Example 3 
     a stethoscope of the third embodiment of the present invention (where an upper head body is made of a high density material, a lower head body is made of a combination of a high density material and a low density material) is compared with stethoscopes of KS-500A, KS-500B and KS-500C types manufactured by Wuxi Kaishun Medical Device Manufacturing CO., Ltd. 
     Comparative data of a stethoscope of the third embodiment of the present disclosure with the KS-500A type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with two sound 
                   
                   
                 comparison 
               
               
                 collecting surfaces 
                 The inventive stethoscope 
                 KS-500A 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Upper head body is made of 
                 Made of only high density 
                   
               
               
                   
                 only high density material, a 
                 material 
               
               
                   
                 lower head body is made of 
               
               
                   
                 combination of high density 
               
               
                   
                 material and low density 
               
               
                   
                 material 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 55 grams × CNY 0.035 
                 98 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 1.93 
                 per gram = CNY 3.43 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 12 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = 0.3 
               
               
                 cost 
               
               
                 Cutting tool 
                 2.32 
                 2.74 
               
               
                 consumption 
               
               
                 Machining time 
                 315 second × CNY 0.011 
                 453 second × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 per second = CNY 3.47 
                 per second = CNY 4.98 
                 time is saved 
               
               
                   
                   
                   
                 by 31% 
               
               
                 Total cost 
                 CNY 8.02 
                 CNY 11.15 
                 Total cost is 
               
               
                   
                   
                   
                 save by 28% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 113 dB 
                 Measured value: 112.7 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 113 dB 
                 Sound source: 114 dB 500 HZ 
                 has no 
               
               
                 sound collecting 
                 500 HZ 
                 Measured value: 102.5 dB 
                 significant 
               
               
                 chamber of the 
                 Measured value: 103 dB 
                   
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 32.5 dB 
                 Measured value: 41.4 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 Measured value: 25.1 dB 
                 500 HZ 
                 20% 
               
               
                 of the stethoscope) 
                   
                 Measured value: 34.8 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 67 grams 
                 98 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     Comparative data of a stethoscope of the third embodiment of the present disclosure with the KS-500B type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with two sound 
                   
                   
                 comparison 
               
               
                 collecting surfaces 
                 The inventive stethoscope 
                 KS-500B 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Upper head body is made of 
                 Made of only high density 
                   
               
               
                   
                 only high density material, 
                 material 
               
               
                   
                 lower head body is made of 
               
               
                   
                 combination of high density 
               
               
                   
                 material and low density 
               
               
                   
                 material 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 53 grams × CNY 0.035 
                 96 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 1.85 
                 per gram = CNY 3.36 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 11 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.27 
               
               
                 cost 
               
               
                 Cutting tool 
                 2.22 
                 2.61 
               
               
                 consumption 
               
               
                 Machining time 
                 327 second × CNY 0.011 
                 466 second × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 per second = CNY 3.59 
                 per second = CNY 5.12 
                 time is saved 
               
               
                   
                   
                   
                 by 30% 
               
               
                 Total cost 
                 CNY 7.93 
                 CNY 11.09 
                 Total cost is 
               
               
                   
                   
                   
                 save by 29% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 122.3 dB 
                 Measured value: 113.4 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 113 dB 
                 Sound source: 114 dB 500 HZ 
                 has no 
               
               
                 sound collecting 
                 500 HZ 
                 Measured value: 106.6 dB 
                 significant 
               
               
                 chamber of the 
                 Measured value: 110.2 dB 
                   
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 35.1 dB 
                 Measured value: 43.2 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 Measured value: 27.5 dB 
                 500 HZ 
                 19% to 27% 
               
               
                 of the stethoscope) 
                   
                 Measured value: 37.4 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 69 grams 
                 100 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     Comparative data of a stethoscope of the third embodiment of the present disclosure with the KS-500C type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with two sound 
                   
                   
                 comparison 
               
               
                 collecting surfaces 
                 The inventive stethoscope 
                 KS-500C 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Upper head body is made of 
                 Made of only high density 
                   
               
               
                   
                 only high density material, 
                 material 
               
               
                   
                 lower head body is made of 
               
               
                   
                 combination of high density 
               
               
                   
                 material and low density 
               
               
                   
                 material 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 57 grams × CNY 0.035 
                 100 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 1.99 
                 per gram = CNY 3.5 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 15 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.37 
               
               
                 cost 
               
               
                 Cutting tool 
                 CNY 2.5 
                 CNY 2.88 
               
               
                 consumption 
               
               
                 Machining time 
                 332 second × CNY 0.011 
                 477 second × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 per second = CNY 3.65 
                 per second = CNY 5.24 
                 time is saved 
               
               
                   
                   
                   
                 by 31% 
               
               
                 Total cost 
                 CNY 8.51 
                 CNY 11.62 
                 Total cost is 
               
               
                   
                   
                   
                 save by 27% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 131.2 dB 
                 Measured value: 120.4 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 114 dB 
                 Sound source: 114 dB 500 HZ 
                 has no 
               
               
                 sound collecting 
                 500 HZ 
                 Measured value: 108.8 dB 
                 significant 
               
               
                 chamber of the 
                 Measured value: 105.5 dB 
                   
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 34.5 dB 
                 Measured value:41.4 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 Measured value: 25.1 dB 
                 500 HZ 
                 17% to 28% 
               
               
                 of the stethoscope) 
                   
                 Measured value: 34.8 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 75 grams 
                 102 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     it can be known from the above comparative data that in the present disclosure, a time for manufacturing the inventive stethoscope is saved by about 30%, a cost for manufacturing the inventive stethoscope is reduced by about 30%, the external noise resistance of the inventive stethoscope is improved by about 20%, a weight of the inventive stethoscope is reduced by about 30%, without significant change to the sound conducting performance, and the stethoscope is easy to carry and has a good appearance. 
     Comparing Example 4 
     a stethoscope of the forth embodiment of the present invention (where an upper head body is made of a combination of a high density material and a low density material, a lower head body is made of only a high density material) is compared with stethoscopes of KS-510A, KS-510B and KS-510C types manufactured by Wuxi Kaishun Medical Device Manufacturing CO., Ltd. 
     Comparative data of a stethoscope of the forth embodiment of the present disclosure with the KS-510A type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with two sound 
                   
                   
                 comparison 
               
               
                 collecting surfaces 
                 The inventive stethoscope 
                 KS-510A 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Upper head body is made of 
                 Made of only high density 
                   
               
               
                   
                 a combination of high 
                 material 
               
               
                   
                 density material and low 
               
               
                   
                 density material, lower head 
               
               
                   
                 body is made of only high 
               
               
                   
                 density material 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 65 grams × CNY 0.035 
                 98 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 2.27 
                 per gram = CNY 3.43 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 9 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.26 
               
               
                 cost 
               
               
                 Cutting tool 
                 2.13 
                 2.72 
               
               
                 consumption 
               
               
                 Machining time 
                 306 second × CNY 0.011 
                 437 second × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 per second = CNY 3.47 
                 per second = CNY 4.98 
                 time is saved 
               
               
                   
                   
                   
                 by 30% 
               
               
                 Total cost 
                 CNY 8.13 
                 CNY 11.15 
                 Total cost is 
               
               
                   
                   
                   
                 save by 27% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 113.7 dB 
                 Measured value: 113.1 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 500 HZ 
                 has no 
               
               
                 sound collecting 
                 Measured value: 101.9 dB 
                 Measured value: 102.4 dB 
                 significant 
               
               
                 chamber of the 
                   
                   
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 32.7 dB 
                 Measured value: 41.8 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 Measured value: 25.7 dB 
                 500 HZ 
                 20% 
               
               
                 of the stethoscope) 
                   
                 Measured value: 34.5 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 74 grams 
                 98 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     Comparative data of a stethoscope of the forth embodiment of the present disclosure with the KS-510B type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with two sound 
                   
                   
                 comparison 
               
               
                 collecting surfaces 
                 The inventive stethoscope 
                 KS-510A 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Upper head body is made of 
                 Made of only high density 
                   
               
               
                   
                 a combination of high 
                 material 
               
               
                   
                 density material and low 
               
               
                   
                 density material, lower head 
               
               
                   
                 body is made of only high 
               
               
                   
                 density material 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 68 grams × CNY 0.035 
                 100 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 2.38 
                 per gram = CNY 3.5 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 9.8 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.24 
               
               
                 cost 
               
               
                 Cutting tool 
                 CNY 2.47 
                 CNY 2.89 
               
               
                 consumption 
               
               
                 Machining time 
                 321 second × CNY 0.011 
                 448 second × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 per second = CNY 3.53 
                 per second = CNY 4.92 
                 time is saved 
               
               
                   
                   
                   
                 by 29% 
               
               
                 Total cost 
                 CNY 8.62 
                 CNY 11.31 
                 Total cost is 
               
               
                   
                   
                   
                 save by 24% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 121.4 dB 
                 Measured value: 118.7 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 500 HZ 
                 has no 
               
               
                 sound collecting 
                 Measured value: 102.4 dB 
                 Measured value: 110.3 dB 
                 significant 
               
               
                 chamber of the 
                   
                   
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 33.5 dB 
                 Measured value: 45 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 Measured value: 28.1 dB 
                 500 HZ 
                 26% 
               
               
                 of the stethoscope) 
                   
                 Measured value: 37.6 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 77 grams 
                 101 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     Comparative data of a stethoscope of the forth embodiment of the present disclosure with the KS-510C type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with two sound 
                   
                   
                 comparison 
               
               
                 collecting surfaces 
                 The inventive stethoscope 
                 KS-510C 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Upper head body is made of 
                 Made of only high density 
                   
               
               
                   
                 a combination of high 
                 material 
               
               
                   
                 density material and low 
               
               
                   
                 density material, lower head 
               
               
                   
                 body is made of only high 
               
               
                   
                 density material 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 66.2 grams × CNY 0.035 
                 102.2 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 2.31 
                 per gram = CNY 3.57 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 8.7 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.21 
               
               
                 cost 
               
               
                 Cutting tool 
                 CNY 2.04 
                 CNY 2.67 
               
               
                 consumption 
               
               
                 Machining time 
                 324 second × CNY 0.011 
                 455 second × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 per second = CNY 3.56 
                 per second = CNY 5 
                 time is saved 
               
               
                   
                   
                   
                 by 29% 
               
               
                 Total cost 
                 CNY 8.12 
                 CNY 11.24 
                 Total cost is 
               
               
                   
                   
                   
                 save by 28% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 125.1 dB 
                 Measured value: 116.4 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 500 HZ 
                 has no 
               
               
                 sound collecting 
                 Measured value: 104.2 dB 
                 Measured value: 11.2 dB 
                 significant 
               
               
                 chamber of the 
                   
                   
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 33.2 dB 
                 Measured value: 45 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 Measured value: 27.9 dB 
                 500 HZ 
                 26% to 27% 
               
               
                 of the stethoscope) 
                   
                 Measured value: 37.3 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 79 grams 
                 96 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     It can be known from the above comparative data that time for manufacturing the inventive stethoscope is saved by 30%, a cost for manufacturing the inventive stethoscope is reduced by about 30%, the external noise resistance of the inventive stethoscope is improved by about 20%, a weight of the inventive stethoscope is reduced by about one third, without significant change to the sound conducting performance, and the stethoscope is easy to carry and has a good appearance. 
     Comparing Example 5 
     a stethoscope of the fifth embodiment of the present invention (where both of an upper head body and a lower head body are made of a combination of a high density material and a low density material) is compared with stethoscopes of KS-520A, KS-520B and KS-520C types manufactured by Wuxi Kaishun Medical Device Manufacturing CO., Ltd. 
     Comparative data of a stethoscope of the fifth embodiment of the present disclosure with the KS-520A type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with two sound 
                   
                   
                 comparison 
               
               
                 collecting surfaces 
                 The inventive stethoscope 
                 KS-520A 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Both of an upper head body 
                 Made of only high density 
                   
               
               
                   
                 and a lower head body are 
                 material 
               
               
                   
                 made of a combination of 
               
               
                   
                 high density material and 
               
               
                   
                 low density material 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 32 grams × CNY 0.035 
                 101 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 1.12 
                 per gram = CNY 3.53 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 21 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.52 
               
               
                 cost 
               
               
                 Cutting tool 
                 CNY 2.27 
                 CNY 2.85 
               
               
                 consumption 
               
               
                 Machining time 
                 287 seondc × CNY 0.011 
                 396 second × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 per second = CNY 3.16 
                 per second = CNY 4.36 
                 time is saved 
               
               
                   
                   
                   
                 by 28% 
               
               
                 Total cost 
                 CNY 7.07 
                 CNY 10.74 
                 Total cost is 
               
               
                   
                   
                   
                 save by 33% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value 113.5 dB 
                 Measured value 112.3 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 500 HZ 
                 has no 
               
               
                 sound collecting 
                 Measured value: 103.3 dB 
                 Measured value: 102.1 dB 
                 significant 
               
               
                 chamber of the 
                   
                   
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value 32.7 dB 
                 Measured value 41.9 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 500HZ 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 Measured value: 25.7 dB 
                 500 HZ 
                 20% 
               
               
                 of the stethoscope) 
                   
                 Measured value: 34.1 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 53 grams 
                 98 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     Comparative data of a stethoscope of the fifth embodiment of the present disclosure with the KS-520B type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with two sound 
                   
                   
                 comparison 
               
               
                 collecting surfaces 
                 The inventive stethoscope 
                 KS-520B 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Both of an upper head body 
                 Made of only high density 
                   
               
               
                   
                 and a lower head body are 
                 material 
               
               
                   
                 made of a combination of 
               
               
                   
                 high density material and 
               
               
                   
                 low density material 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 33.3 grams × CNY 0.035 
                 103 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 1.16 
                 per gram = CNY 3.6 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 23.5 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.58 
               
               
                 cost 
               
               
                 Cutting tool 
                 CNY 2.33 
                 CNY 2.94 
               
               
                 consumption 
               
               
                 Machining time 
                 276 second × CNY 0.011 
                 401 second × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 per second = CNY 3.03 
                 per second = CNY 4.41 
                 time is saved 
               
               
                   
                   
                   
                 by 32% 
               
               
                 Total cost 
                 CNY 7.1 
                 CNY 10.95 
                 Total cost is 
               
               
                   
                   
                   
                 save by 36% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value 115.7 dB 
                 Measured value 112.3 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 500 HZ 
                 has no 
               
               
                 sound collecting 
                 Measured value: 108.3 dB 
                 Measured value: 104.4 dB 
                 significant 
               
               
                 chamber of the 
                   
                   
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 33.1 dB 
                 Measured value: 43.6 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 Measured value: 27.4 dB 
                 500 HZ 
                 24% to 25% 
               
               
                 of the stethoscope) 
                   
                 Measured value: 35.9 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 56 grams 
                 108 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     Comparative data of a stethoscope of the fifth embodiment of the present disclosure with the KS-520C type of stethoscope are shown below. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Type of stethoscope 
                   
                   
                 Data 
               
               
                 with two sound 
                   
                   
                 comparison 
               
               
                 collecting surfaces 
                 The inventive stethoscope 
                 KS-520C 
                 result 
               
               
                   
               
             
            
               
                 Structure 
                 Both of an upper head body 
                 Made of only high density 
                   
               
               
                   
                 and a lower head body are 
                 material 
               
               
                   
                 made of a combination of 
               
               
                   
                 high density material and 
               
               
                   
                 low density material 
               
               
                 Name of high 
                 Stainless steel (type 304) 
                 Stainless steel(type 304) 
               
               
                 density material 
               
               
                 Material 
                 31.5 grams × CNY 0.035 
                 106 grams × CNY 0.035 
               
               
                 consumption and 
                 per gram = CNY 1.1 
                 per gram = CNY 3.71 
               
               
                 cost 
               
               
                 Name of 
                 Polyformaldehyde (POM) 
               
               
                 low-density 
               
               
                 material 
               
               
                 Material 
                 22.5 grams × CNY 0.025 
               
               
                 consumption and 
                 per gram = CNY 0.56 
               
               
                 cost 
               
               
                 Cutting tool 
                 CNY 2.5 
                 CNY 2.96 
               
               
                 consumption 
               
               
                 Machining time 
                 290 second × CNY 0.011 
                 388 second × CNY 0.011 
                 Machining 
               
               
                 and cost 
                 per second = CNY 3.19 
                 per second = CNY 4.26 
                 time is saved 
               
               
                   
                   
                   
                 by 26% 
               
               
                 Total cost 
                 CNY 7.35 
                 CNY 10.93 
                 Total cost is 
               
               
                   
                   
                   
                 save by 33% 
               
               
                 Sound conducting 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 Sound 
               
               
                 performance test 
                 1000 HZ 
                 1000 HZ 
                 conducting 
               
               
                 (where a sound is 
                 Measured value: 120.3 dB 
                 Measured value: 125 dB 
                 performance 
               
               
                 collected by a 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 500 HZ 
                 has no 
               
               
                 sound collecting 
                 Measured value: 111 dB 
                 Measured value: 108.6 dB 
                 significant 
               
               
                 chamber of the 
                   
                   
                 change 
               
               
                 stethoscope) 
               
               
                 External noise 
                 Sound source: 114 dB 
                 Sound source: 114 dB 
                 External 
               
               
                 resistance 
                 1000 HZ 
                 1000 HZ 
                 noise 
               
               
                 performance test 
                 Measured value: 31.4 dB 
                 Measured value: 43.3 dB 
                 resistance is 
               
               
                 (where a sound is 
                 Sound source: 114 dB 500 HZ 
                 Sound source: 114 dB 
                 improved by 
               
               
                 collected by a back 
                 Measured value: 28.5 dB 
                 500 HZ 
                 25% to 28% 
               
               
                 of the stethoscope) 
                   
                 Measured value: 37.8 dB 
               
               
                 Aesthetics (two 
                 With two colors mixed 
                 Monochrome 
                 Visual effect 
               
               
                 colors mixed) 
                   
                   
                 is improved 
               
               
                 Portability 
                 50 grams 
                 92 grams 
                 Easy to carry 
               
               
                 (in weight) 
               
               
                   
               
            
           
         
       
     
     It can be known from the above comparative data that time for manufacturing the inventive stethoscope is saved by about 30%, a cost for manufacturing the inventive stethoscope is reduced by about 30%, the external noise resistance of the inventive stethoscope is improved by about 20%, a weight of the inventive stethoscope is reduced by about one third, without significant change to the sound conducting performance, and the stethoscope is easy to carry and has a good appearance.