PLUG TO BE INSERTED INTO THE EAR CANAL FOR NOISE ATTENUATION, AND INSTRUMENT FOR INSERTING SUCH A PLUG

Abstract: The invention relates to an ear plug to be inserted into the ear canal and this plug is according to the invention shaped in an oval cross sectional form. The invention also relates to the use of a cylinder (12) which is completely open at one end (13) thereof, with a piston (17) displaceable in the cylinder, which has a piston rod (18) projecting from the other end of the cylinder, for insertion and orientation of an ear plug by forcing the plug received in the cylinder through said one open end into the ear canal with this end engaged to the mouth of the ear canal.

Description: PLUG TO BE.INSERTED INTO THE EAR CANAL FOR NOISE ATTENUATION, AND INSTRUMENT FOR INSERTING SUCH A PLUG Plugs for noise attenuation (ear canal protec¬ tors) in existing embodiments consist of a cylindri¬ cal plug of, for example, elastically defor able foamed plastic material or fiber material and presently are considered to be the most comfortable and effective hearing protector. Unlike hearing protectors in the form of ear muffs they do not cause inconvenient perspiration. Nevertheless, it has been found that many people experience dis¬ comfort and practical problems in connection with the use of ear plugs as hearing protectors. Dis¬ comfort can appear principally in the form of itch¬ ing but also in the form of pressure, eczema, head¬ ache and heat. The insertion of the ear plug also involves a practical problem to many people. The plug is inserted into the ear canal by first com¬ pressing it by rolling it between, the fingers. When the plug is to be inserted into the ear canal, for example into the left ear, the plug is held by the left hand while the external ear is drawn upwards and outwards with the right hand, and vice versa if the right ear is concerned. This is the easiest way ■ to direct the compressed plug into the ear canal. After the insertion the plug is kept in place with a finger tip for a few seconds during the expansion thereof inside the ear canal. It is important that the ear plug fills approximately the outer half of the ear canal and it is also important that the ear plug tightly engages the wall of the ear canal after the expansion. Due to the fact that the shape of the ear canal varies from one individual to another, the ear plug must be compressed .sufficiently before the insertion thereof in order to pass freely into the ear canal to the intended position therein. In most cases the ear canal is narrow and slit-shaped, which means that the ear plug simply cannot be inserted or, alternatively, that it will be located in the ear in a bad way with regard to noise attenuation, or even in a painful way. An investigation has been made in order to de¬ termine how well the ear plugs of existing embodi¬ ments, i.e. of the cylindrical shape, are adjusted to the anatomy of the ear canal, by measuring the size of the outer ear Canal of ear canal castings of the type produced- for use in the production of ear canal inserts for hearing aids. On the castings measurements were made of the height and the width of the ear canal on two different locations each, and by guidance of the measurements the appearance of the ear canals were subjectively judged as slit- shaped, oval or round (circular) . By studying the material the ratio of width and height of ear canals with different shapes has been put together accord¬ ing to TABLE I below. In the subjective judgement thus made slit- shaped ear canals have been found to have an ap- proximate ratio of width and height which equals 1/2, oval 2/3 and round 1/1, the slit-shaped and oval ear canals together representing 95% of ail measured ear canals (ear canal castings) . Existing ear plugs of the above mentioned type which are used as ear canal protectors against noise have generally round shape herein referred to as principally circular form. They have a diameter of the order of 12 mm in fully expanded condition. At maximum compression of such an ear plug made of foamed plastic material, which it often is, it is possible to reduce the diameter of the ear plug to 5 mm, which means that many people with slit-shaped ear canals have difficulties in inserting such a plug into the ear canal. Moreover, it has been found that many people with slit-shaped ear canals ex¬ perience great surface pressures after the expansion of the ear plug, which results in discomfort. On the basis of the observations thus made it is suggested according to the invention to provide an ear plug to be inserted into the ear canal according to the characterizing feature of claim 1, i.e. to make the plug oval in cross section. Preferred detail embodiments of such a plug are defined in claims 2-5. The plug according to the invention is not intended as an ear canal protector only but can also be provided for connection to a loud-speaker device or another sound transmitter (as an earphone for a portable radio receiver and/or tape recorder or a dictating machine, or as an ear plug for a hearing aid) . It has been found that the ear plugs in practice are not always inserted in the proper way at the work places. Both hands must be used at the inser- tion of the ear plug in the conventional way as has been described above, and it is then difficult to control by yourself how the insertion is made. The plug is not always sufficiently compressed, and often becomes contaminated by the compressing thereof with following risk that it will cause ir¬ ritation and/or inflammation of the ear canal. More¬ over, it is not possible to adjust the ear plug to the shape of the ear canal at the compressing and the insertion, which often leads to pressure dis¬ comfort and/or leakage especially as the ear canal in most cases is not circular but oval in cross sec¬ tion. The purpose of the invention is to facilitate the proper insertion of the plug into the ear canal by the insertion and, which is especially important when an oval ear plug is concerned, also the orien¬ tation of the plug are better controlled with fol¬ lowing good fit between the ear plug and the ear canal, and to improve hygienics at the insertion. With this in view the use of the device defined in claim 6 for the insertion of the ear plug is sug¬ gested according to the invention. A cross section of the cylinder then can be chosen which is dimen¬ sioned and/or shaped so as to be adapted to the ear canal of the user, and causes such compression of the ear plug that it certainly will not interfere with the wall of the ear canal at the insertion thereof. The ear plug can be inserted comfortably by the piston being pressed into the cylinder, -the direction of the insertion of the ear plug and the orientation thereof being easily adjusted to the direction and shape, respectively, of the ear canal. Moreover, the insertion depth can be accurately controlled, and the plug can be kept oriented after the shape of the ear canal at- the insertion. For further explanation of the invention refer¬ ence is made to the accompanying drawings in which FIG 1 is a perspective view of an ear plug for noise attenuation according to the invention, FIG 2 is an end view of the ear plug in FIG 1 with the axes of the oval end surface shown in, FIG 3 is a partly broken perspective view of an ear plug to be connected to a loud-speaker device, FIG 4 is an axial cross sectionas view which shows an embodiment of an instrument for the insertion of an ear plug, and FIG 5 is a comparative diagram showing the attenuation which is achieved with ear plugs which have been inserted manually in a conven¬ tional way and by using the instrument described herein, respectively. In FIG 1 an elastically deformable ear plug 10 is shown which is to be used as noise attenuating ear canal protector. It can be made of flexible foamed plastic material, for example, expanded polyurethane, polyvinylchloride or polyethylene, or also of foamed latex, and it can be produced in a mould or be stamped from sheet material. It has oval or elliptic cross sectional' form. With plugs of two different sizes of , this shape the practical need of such ear plugs can be satisfied on the basis of the examination results aaccounted for above. With reference to FIG 2 these ear plugs can thus be dimensioned: Embodiment I Y-axis 15 mm X-axis 10 mm Cross section area 117.8 mm 2 X/Y = 0.67 Embodiment II Y-axis 11 mm X-axis 7 mr. Cross section area 60.1 mm 2 X/Y = 0.64 The first embodiment serves the need of 2/3 of the users and the second embodiment serves the need of 1/3 of the users if foamed plastic material is used. Generally, it can be said that the Y-axis should have a length of between 6 and 15 mm and the X-axis a length of between 3 and 10 mm. The X/Y ratio should be of the order of 0.3 - 0.95. FIG 3 shows an ear plug 10' to be used as an earphone of a portable radio and/or tape recorder, in a hearing aid, in a dictating machine, or other sound device. It is required that such a plug should shut out surrounding noise and thus make the sound from the connected sound device clearer and easier to hear, so that lower volume of the sound can be used which is lenient for the ears. Especially in hearing aids the ear plug should also prevent feed back. These requirements are satisfied by the ear plug effectively sealing in the ear canal. According to FIG 3 the plug 10' is of the same design as the plug in FIG 1 but it has a cylindrical tube 11 passing ' centrally therethrough, which can consist e.g. of soft or hard plastic material which is glued or otherwise attached to the ear plug on the ex¬ ternal surface thereof. It projects from one end of the ear plug, and to this end a loud-speaker device can be connected directly, or this loud-speaker device can also be located at another place, for example, in the connected sound device and be con¬ nected by means of a ductible plastic hose to the projecting end of the tube 11. The instrument shown in FIG 4 comprises a cylinder 12 with circular or oval cross section which at one end thereof is connected to an end cover 13 which forms two projecting finger grips 14. The cylinder 12 is open at the other end at 15, and the aperture has the same cross section as the rest of the cylinder. In the last mentioned end a collar 16 is provided on the outside of the cylinder. This collar should be designed in a suitable way so as to be engaged with the mouth of the ear canal. A piston 17 with a piston rod 18 can be axially displaced in the cylinder. The piston rod extends through the end cover 13 and at the outer end thereof is provided with a head 19 so that the instrument can be grasped with two fingers, one at each finger grip, and with the thumb engaging the head 19 the piston 17 can be displaced through the cylinder to the open end thereof. An elastically deformable plug 10 (or 10') is inserted into the cylinder 12 in compressed condi¬ tion, and this plug can be of the embodiment de¬ scribed herein,or a conventional plug with circular cross section. When the instrument at the collar 14 has been engaged with the mouth of the ear canal, the plug, can be pressed into the ear canal by the piston 17 being displaced through the cylinder the plug being forced from the cylinder with the instrument held in such a position that the ear plug, when being forced out from the cylinder and being inserted into the ear canal has the proper direction and the proper orientation in order to be properly positioned in the ear canal, sealingly engaging the bounding walls thereof, in order that the ear plug will effectively shut surrounding noise from the ear canal. The instrument can be adjusted as to the cross dimension and the cross sectional shape of the cylinder 12 to ear plugs of different sizes and shapes. In the compressed condition thereof also a plug with oval cross sectional shape can fit into a cylinder with circular cross section so as to ex¬ pand, after the insertion into the ear canal, to the oval shape thereof. The advantage by using the instrument for the insertion of the ear plug is that the plug with respect to the oval shape thereof can be oriented in the cylinder in such a way that the orientation of the oval cross sectional shape co¬ incides with the oval shape of the ear canal. It is obvious that the instrument according to the invention can be used for inserting plugs ir¬ respective of the cross sectional shape thereof but it is advantageous that the instrument can be used especially with plugs having oval cross sectional shape due to the fact that such plugs are better adjusted to the shape of the ear canal of most people. By the instrument being provided with the collar 16 the plug is prevented from being inserted too far into the ear canal. It is namely important, as men¬ tioned above, that the plug substantially fills the outer half of the ear canal but does not go too far into the same since difficulties in removing the plug can arise. When ear plugs according to FIG 3 are being used the piston can have an axially projecting guiding pin which is received in the tube 11 in the plug, or also a wartlike projection which passes into the mouth of this tube, so that the tube is not tipped sidewards in the soft material of the plug when the piston presses against the end of the plug. A study has shown that the insertion of the ear plug can be made by considerably higher precision by using the instrument described above than by insert¬ ing in the conventional way which is demonstrated by the ear plug providing a better attenuation. The real-ear attenuation of 18 test persons (36 ears) with ear plugs inserted by hand was measured by means of a computerized Bekesyaudio etri via special hearing telephones and thereafter the measurement was repeated with ear plugs which had been inserted by means of the instrument described in connection with FIG 4. The measured attenuation at the different fre¬ quences for each of the two insertion methods are plotted in the diagram of FIG 5. From the results shown it is gathered that the instrument method gives a better or as good attenua¬ tion at all the tested frequences. Moreover, there is a tendency of decreased variation of the values when this method is used. The conclusion can there¬ fore be drawn that the use of the described instru¬ ment can be of great importance in order to increase the "practical" attenuation which is achieved by means of an elastically deformable ear plug by a standardized insertion procedure. Moreover, the instrument contributes to a more hygienic use of the ear plug which thereby can decrease the frequency of itching and irritation in the ear canal.

Claims: CLAIMS 1. Ear plug _o be inserted into the ear canal, c h a r a c t e r i z e d in that the plug has oval cross sectional shape. 2. Ear plug according to claim 1, c h a r ¬ a c t e r i z e d in that it can be elastically deformed. 3. Ear plug according to claim 1 or 2, c h a r a c t e r i z e d in that the major axis of the oval cross section has a length of between 6 and 15 mm, and the minor axis thereof has a length of between 3 and 10 mm. 4. Ear plug according to claim 1 or 2, c h a r a c t e r i z e d in that the ratio of the length of the minor axis and the major axis of the oval cross section is of the order of between 0.3 and 0.95. 5. Ear. plug according to claim 1, c h a r ¬ a c t e r i z e d in that centrally through the ear plug (10') there is provided a tube (11) which is open at both ends to be connected to a sound trans¬ mitter. 6. The use of a cylinder (12) which is com¬ pletely open at one end (13) thereof, with a piston (17) displaceable in the cylinder, which has a piston rod (18) projecting from the other end of the cylinder, for insertion and orientation of an ear plug by forcing the plug received in the cylinder through said one open end into the ear canal with this end engaged to the mouth of the ear canal. 7. The use according to claim 1, wherein the ear plug can be elastically deformed and compressed before it is inserted into the cylinder (12) in order to expand in the ear canal after it has been forced from the cylinder. 8. The use according to claim 6 or 7 wherein said open end (15) is engaged with the ear at the mouth of the ear canal at an external collar (16) provided at that end to limit the insertion of the end into the mouth of the ear canal. 9. The use according 'to any of claims 6-8, wherein the ear plug as well as the cylinder (12) has oval cross section.

Inventors: BENNRUP SIGRID, IVARSSON ALF, BENNRUP, SIGRID, IVARSSON, ALF
Applicants: BENNRUP SIGRID, IVARSSON ALF, BENNRUP, SIGRID, IVARSSON, ALF
Application year: 1990
Main classification: A61F11
IPC codes: A61F11