Patent Application: US-76523404-A

Abstract:
i have discovered a way to improve the sound of musical instruments that utilize a soundboard or sound generating surface such as found in stringed musical instruments . i accomplished this by establishing a pronounced textured acoustical diffusing surface to one or more of the overall surfaces of the vibrating sound generating surface or soundboard of a stringed musical instrument creating greater surface area from which to generate greater acoustic energy . the result - compared to existing methods of improving the performance of soundboards of stringed musical instruments - is improved volume , timbre , projection , and tonality and sustain of the acoustical sounds produced by the stringed musical instrument .

Description:
this invention includes textured surfaces for sound transmitting panels , as well as methods for making such surfaces . for a first general embodiment of the invention , textured surfaces are provided on at least one major sounding surface of a wood soundboard that is to be acoustically driven by the strings of a stringed musical instrument . the textured soundboard surfaces are preferably created by compressing the surface material of earlywood growth rings , or grains , to form a series of generally parallel grooves , each of which lies between a pair of latewood growth grains . each groove is created with a scribing operation using either a stylus or rotating wheel tool , similar to a pizza cutter , of an appropriate size and shape . this is considered the preferred embodiment for wood soundboards because compression of only the surface material of earlywood growth grains does not adversely affect the structural integrity of the panel . in fact , the partial compression of earlywood growth grains not only increases the surface area of the panel , but increases its stiffness ( i . e ., modulus of elasticity ) as well . alternatively , a pattern can be stamped or rolled into the surface without regard for the position of earlywood and latewood grains . though not a preferred method of increasing the surface area of a wood sound transmitting panel , it would be far less labor intensive to press or roll a pattern onto a wood surface without regard to the position of the different grain regions . referring now to the wood panel 300 of fig3 the upper surface of wood panel 100 of fig1 has been partially treated with a stylus 301 having a paraboloid - shaped tip 302 . more specifically , the tip 302 has the shape of a parabola that has been rotated 180 degrees about its axis of symmetry . the paraboloid tip 302 is preferably of a gauge that is wide enough to span the entire width of each earlywood grain 101 , as positioned between an adjacent pair of latewood grains 102 . the gauge of the tip can be selected for each earlywood grain width . applying downward pressure that is preferably constant for each earlywood grain 101 , the stylus 301 is drawn longitudinally on top of each earlywood grain 101 , thereby compressing surface material of the earlywood grain 101 , and leaving a mechanically depressed groove 303 having the inverse cross - sectional profile as that of the tip 302 . the compressed earlywood material 304 at the bottom of the groove 303 assumes a modulus similar to those of the tangential latewood 102 . thus , the compressed earlywood material 304 becomes a bridge of “ virtual ” latewood over the underlying uncompressed earlywood material 305 and between adjacent pairs of latewood grains 102 . empirical evidence shows that this additional vibrational axis — a quasi - horizontally polarized modulus of stiffened earlywood — apparently helps to separate possible overtones and sound cancellations , thereby generating improved intonations across the spectrum of sounds produced by the soundboard . grooves 303 of constant or varying depth may be created by varying the downward pressure on the stylus 301 or by repeating the grooving step multiple times for each earlywood grain 101 . referring now to fig4 the upper surface of wood panel 300 of fig3 has been fully treated so that all grooves 303 have a parabolic cross section and are of generally uniform depth . individually , the grooves are designated by the general item number 303 , followed by a specific letter identifier . thus , the four grooves of which a complete cross section is shown are labeled 303 - a , 303 - b , 303 - c and 303 - d . this same numbering scheme will be followed for subsequent similar drawing figures . as a result of the grooving process , the resulting soundboard 400 has been endowed with different resonance properties . the wood panel of the soundboard 400 is now stiffer , having a larger modulus of elasticity , although its mass remains unchanged . in addition , the surface area of the soundboard 400 has been more than doubled by the grooving process . this increase in surface area translates into greatly enhanced resonance . referring now to fig5 a rotating disk tool 500 is shown which may be used in place of a stylus 301 having a paraboloid tip 302 . the rotating disk tool 500 has a disk 501 that is rotatably mounted within a frame / handle 502 . it will be noted that the rotating disk 501 is radially symmetrical , and has a circumferential edge 503 with a parabolic profile . referring now to fig6 the soundboard 400 is shown in an isometric view . it can be clearly seen that each groove 303 extends the full length of its associated earlywood grain , between two latewood growth grains 102 . referring now to fig7 the soundboard 400 has been further treated by grooving its lower surface so that it is a mirror image of the upper surface . the benefits accruing to the resulting soundboard 700 are cumulative , with the total surface area being more that four times that of the surface area of the untreated ( i . e ., ungrooved ) soundboard 300 . resonance and stiffness are , thus , also increased . by grooving both sides of the soundboard 700 , optimum resonance results are obtained . referring now to fig8 each of the earlygrowth grains 101 on the upper surface of soundboard 100 have been grooved to varying depths using at least one stylus 301 having a paraboloid tip 302 or a rotating disk tool 500 having circumferential edge 502 with a parabolic profile . the resulting soundboard 800 may have improved responsiveness to different frequencies of sound waves . four complete grooves of parabolic cross section are shown on the completed soundboard 800 : 801 - a , 801 - b , 801 - c and 801 - d . the regions of compressed earlywood at the bottom of each such groove are 802 - a , 802 - b , 802 - c and 802 - d . as the depth of each of the grooves 803 - a , 803 - b , 803 - c and 803 - d is of a different depth , the degree of earlywood grain compression in regions 802 - a , 802 - b , 802 - c and 802 - d also varies . referring now to fig9 each of the earlygrowth grains 101 on the upper surface of wood panel 100 has been grooved to a constant depth using either a stylus 801 having hemispherical tip 902 or a rotating disk tool similar to that of fig4 but with a disk having circumferential edge of semicircular cross section ( not shown ). the resulting soundboard 900 has four grooves of semicirular cross section : 901 - a , 901 - b , 901 - c and 901 - d . the regions of compressed earlywood at the bottom of each such groove are 902 - a , 902 - b , 902 - c and 902 - d . referring now to fig1 , each of the earlygrowth grains 101 on the upper surface of wood panel 100 have been grooved to a constant depth using either a stylus 1001 having a doomed conical tip 1002 or a rotating disk tool similar to that of fig4 but with a disk having circumferential edge of rounded - v - shaped cross section . the resulting soundboard 1000 has four grooves of rounded - v - shaped cross section : 1003 - a , 1003 - b , 1003 - c and 1003 - d . the regions of compressed earlywood at the bottom of each such groove are 1004 - a , 1004 - b , 1004 - c and 1004 - d . besides circular and parabolic shaped valleys , other corrugation and texture types may be used to increase the soundboard surface area . referring now to fig1 , a wood panel or laminar sheet of some other sound resonating material 1100 , has been stamped with a repeating pyramidal textured surface pattern 1101 on its upper surface 1102 in order to increase its surface area . if acute angle θ of each pyramid is 45 degrees , the increase in surface area will be the original surface area multiplied by the square root of 2 , or about 1 . 412 . of course , the greater the angle θ , the greater the increase in surface area . the pattern is stamped on the panel or sheet using either a stamp having the inverse pattern as the finished product , or a roller on which the inverse pattern has been applied . it is well known that soundboards for stringed musical instruments can be made of a number of resonant materials , including wood , sheet metal and even composite materials . by virtue of this geometry , wave energy fluidically traveling throughout the non - rectangular soundboard can assumedly escape easier through the textured surface pattern 1101 and excite a greater mass of air molecules in contact with said surface , resulting in a larger quantity of air pressure generated sound waves as observed during tests . the results are similar to why a timpani ( kettledrum ) can be much louder more dynamic than a bongo . another aspect of the present invention is the creation of so called waveguides and emitters from the peaks and valley of the pronounced textured surface . for example , the grooves of the textured soundboards of fig3 , 7 , 8 , 9 and 10 guide and spread the sound waves across the entire surface of the soundboard . it is assumed that as the sound waves are launched by vibration into the air , the peaks 406 ( i . e ., the exposed tops ) of the latewood grains 102 of any of the aforementioned soundboards , cause to help emit , focus and launch air pressure waves more conically directed into the stringed instrument sounding chamber creating a more concentrated acoustic effect . as a result , greater sound amplification can be achieved and has been demonstrated during tests . it should also be noted that the peaks 406 of the latewood grains 102 , whether they be flat ( as shown ), arched , rounded , or peaked , will function as sound emitters . with the aim of increasing soundboard surface area as much as possible by texturing , the sizes of the textures and corrugations on the textured soundboard surface may have , as various uniform and non - uniform depths and widths depending upon the application of the invention on wood or non - wood materials used in vibrating soundboards and similar sound generating surfaces . the texturing widths may range from few parallel or non - parallel corrugations in the textured soundboard surface to thousands of parallel or non - parallel corrugations or impregnated regular or irregular singularities per unit of surface area . depending upon the stiffness and mass density of the soundboard , the depth of the corrugations and impregnations on the textured soundboard surface may range from a depth nearly equal to the thickness of the soundboard to barely applied in the overall surface . for what are presently considered preferred embodiments of the invention , texture depth should generally range between 25 % to 100 % of the width of a single texture feature . thus , for a grooved soundboard , the depth of each groove should preferably range between 25 % to 100 % of the width thereof . texture widths will generally measure less than the thickness of the soundboard . this flexible aspect of the present invention enables the surface of any stringed instrument sounding surface various and graduated texturing implementations such as but not limited to deeper and broader corrugations or impregnations ranging to narrower and shallower corrugations , stamping or impressions variously mixed or separated into discrete regions on the same soundboard . to create a textured soundboard , which achieves the desired results , the present invention may be carried out with or without respect to the earlywood or latewood grains of the wood because certain woods and non - wood materials do not have such growth rings or grains of dissimilar modulus properties to follow along with tooling to create a plurality of grooves as described in one embodiment of the invention . creating pronounced grooves , corrugations and textures in such non - grained wood or non - wood materials used for soundboards is within the scope and object of the present invention . furthermore , soundboards made of wood or non - wood materials could have applied textured patterns in more than one direction crossing each other from obtuse or acute angles , and leaving uniform or non - uniform flat or rounded diamond patterns , or flat or rounded waffle - faced surfaces . furthermore , a plurality of welled or conical patterns may be produced in all or part of the soundboard surface by tooled stampings , impressions or molding processes . referring now to fig1 , an alternative embodiment may be achieved by bonding a “ skin ” of pre - textured material 1201 to the surface of a laminar soundboard 1202 to create a composite soundboard 1200 and achieve similar results . this skinning method and process of affixing a second textured structure to a first soundboard surface to create a pronounced textured and corrugated soundboard surface is to be considered within the scope of the present invention . the textured material layer may be either flexible , semi - rigid , or rigid . certain automated processes may be employed to create corrugated and textured soundboard surfaces . for example , cnc micro - surface - routing of the earlywood grains using optically - guided mechanical or scanning laser etching equipment may be used . using such machinery , an amount of earlywood grain may be removed from the surface of a wood soundboard sufficient to produce corrugation or texturization on the surface thereof . the same types of automated processes may be employed with respect to non - wood panels . in addition , soundboards made of non - wood or composite materials can be pressed , extruded , molded , laid - up , tooled , cut and finished in such a way as to leave textures and corrugations of various widths and shapes in the surface of stringed instrument and their soundboards not unlike those described herein . since the materials used in this extension of the present invention are non - wood , the corrugation pattern may be applied in more than one direction crossing each other from obtuse to acute angles leaving flat or rounded diamond patterns or flat or rounded waffle faced surfaces including wells and cones . sand , bead or sublimable particle blasting may be used to selectively remove softer earlywood leaving a corrugated surface with the harder latewood remaining exposed in peaks not unlike the individually worked earlywood grains compressed by the stylus described herein . this sand blasting process may also be used on masked non - wood materials leaving a desired surviving texture in the soundboard . another possible option is to use a process similar to a shot - peening process which would compact the softer earlygrowth grains more than the more dense lategrowth grains , without removing significant amounts of earlygrowth material , in order to create a soundboard that is structurally similar to those shown in fig3 , 7 , 8 , 9 and 10 . that is , a soundboard so created would have both greater surface area and a greater modulus of elasticity . referring now to fig1 , a textured soundboard 1300 has been created by removing - rather than compacting - earlywood growth material from the upper surface . because the earlywood grain regions 1301 are less dense than the latewood grain regions 1302 , the earlywood growth material will be removed at a faster rate than the latter when the surface is subjected to particle blasting . the particles may be sand , plastic beads or sublimable particles such as carbon dioxide pellets . the downward arrows 1303 represent the blasting process . the resulting soundboard 1300 , although not considered to be the preferred embodiment of the invention , does have increased surface area . it will be noted that the absence of compressed earlygrowth material between adjacent pairs of latewood grain regions 1302 results in a soundboard that likely has less stiffness than the untreated soundboard . it will also be noted that the upper surface 1304 of each latewood growth has rounded shoulders 1305 . this is a result of only partial selectivity in the blasting process . that is , both the earlygrowth regions 1301 and lategrowth regions 1302 are simultaneously abraded , but at different rates . referring now to fig1 , a textured soundboard 1400 has been created by using a shoot peening process . the difference between the process used for soundboards 1400 and 1300 reside in the projectiles that are used to collide with the soundboard surface , the energy used to accelerate the projectiles , and the particle angle of attack . for the shot peening process , generally smooth and spherical particles 1403 impact the soundboard 1400 orthogonal to its upper surface . the energy is not so great that material is removed from the upper surface , but rather simply compacted in regions 1404 . as the earlygrowth regions 1401 are of lesser density than the lategrowth regions 1402 , they are compacted at a faster rate than the lategrowth regions 1402 . any of the textured soundboards illustrated in fig3 , 7 , 8 , 9 , 10 , 11 , 12 , 13 and 14 may be coated with at least one preservative coating . such a preservative coating may be selected from the group consisting of varnish , lacquer , shellac , polyurethane resin and polyester resin . referring now to fig1 and 16 , a loudspeaker 1500 manufactured in accordance with the present invention has a radially grooved speaker cone 1501 which increases its surface area as compared to a cone made of generally laminar material . the speaker cone 1501 is electromagnetically driven by an electromagnet assembly 1502 that is attached to both the frame 1503 of the loudspeaker 1500 , and to the rear of the speaker cone 1501 . the speaker cone 1501 is preferably molded from either cellulose fiber material or from a polymeric plastic material . the central diaphragm 1504 of the loudspeaker 1500 may also be molded from the same types of materials and provided with a textured surface to increase its surface area . the increase in surface area of the speaker cone 1501 and of the central diaphragm 1504 will increase the volume of sound generated thereby as compared to a conventional loudspeaker , all other parameters ( e . g ., the input current and driver efficiency ) being equal . referring now to fig1 , the radial grooves 1701 in the speaker cone 1501 are clearly visible in this thin - slice view . although only the radially - grooved pattern has been shown in a loudspeaker embodiment , it should be understood that this invention contemplates the use of any other pattern that can be stamped or molded on a laminar material . such pattern may include a waffle pattern , random three - dimensional patterns , or a pattern of repeating geometric figures , such as the contiguous pyramids shown in fig1 . however , for a loudspeaker cone application , the pattern would be imprinted or molded on both sides of the laminar cone or diaphragm material , in the same manner that a paper fiber egg carton as a three - dimensional pattern on both upper and lower surfaces . referring now to fig1 , a router bit 1800 having a parabolic tip 1801 may be rotated at high speed about its central axis 1802 to removed early growth material in a computer - controlled , optically - guided texturization operation . the technology for guiding and controlling such a cutting operation is well known in the art . referring now to fig1 , a soundboard 1900 has been texturized using a computer - controlled , optically - guided scanning laser ( not shown ). the laser has removed ( i . e ., burned ) material in a step - like fashion to create a series of stepped trenches 1902 in the earlywood regions 1901 . the lategrowth regions 102 are untouched . the technology for guiding and controlling a laser burning operation is well known in the art . although only several embodiments of the invention have been disclosed herein , it will be obvious to those having ordinary skill in the art that changes and modifications may be made thereto without departing from the scope of the invention as hereinafter claimed . “ geometry , proportion and the art of lutherie : a study of the use , and esthetic significance of geometry and numerical proportion in the design of european bowed and plucked string instruments in the 16 th , 17 th and 18 th centuries .” by kevin coates . published by oxford at the clarendon press , 1985 , david stanford , printer . 170 pp . library of congress ml755 . c6 1983 787 ′. 672 83 - 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