DRUM PITCH MODULATION

Abstract: A pitch modulator for momentarily increasing the pitch of a drum (12) and method of increasing the pitch of a drum (12) comprising mounting integrally on a drumhead membrane (11) a pitch modulator comprising a flat ring-like construction (15) of flexible stretch-resistant material having one flat side coated with adhesive material (17) which unites said ring-like construction (15) with said drumhead membrane (11) to form a unitary flexible stretch-resistant structure with an appreciable portion of the surface of said drumhead membrane (11).

Description: DRUM PITCH MODULATION The present invention relates generally to a drum structure and more particularly to an improved drumhead and means for producing momentarily a large change in the fundamental pitch of a drum when the drum is struck a sharp blow; thereby adding interest and color to the usual rhythmic role of a drum. The playing characteristics of a drum which a drummer desires depends on the musical style of the drummer and on the type of music played. Various means are presently employed to affect the playing characteristics of a drum, such as a tom-tom type drum, and modify the modes thereof. Normally, equal tension is applied to the drumhead in all directions. When the tension is uneven beats are heard when the drum is struck. If it is desired to shorten the decay time of the drum modes and give the drum a dull tone quality, dampen¬ ing means are used, such as attaching a piece of cloth to the drum membrane or taping a small patch of cloth or plastic foam to the drumhead membrane. < Other means are used for increasing the amount of pitch change produced when the drum is struck a sharp blow. For example, loosening one of the tuning screws to effect a change in the pitch is one expedient used, however, the drum then does not hold its tuning very well. Another procedure is to adhesively secure to the center of the drum¬ head, a dot or small patch of flexible plastic material which gives the drumhead a "tubby" sound and tends to increase the decay time of the fundamen¬ tal mode while causing the fundamental mode to OMPI have a change in frequency as a function of the displacement thereof. Electronic means have also been used to produce a simulation of a pitch change, but such means are expensive and not practical for many to use. The present invention provides an inexpensive way of effecting a desirable significantly large momentary increase in the pitch of a drum when the drum is struck a sharp blow and at the same time effecting a significant decrease in the decay time of the fundamental tone or mode of a drum which will be apparent from the following detailed descriptions and claims to follow when read in conjunction with the accompanying drawing, wherein: Fig. 1 is a perspective schematic view of a drum having a compound drumhead of the present invention mounted on one end thereof; Fig. 2 is a schematic vertical sectional view of the drumhead of Fig. 1; Fig. 3 is a schematic vertical sectional view of a modified form of the drumhead invention of the present invention; Fig. 4 is a schematic vertical sectional view of a further modified form of the drumhead invention of the present invention; Fig. 5 is a schematic vertical sectional view of a still further modified form of the drumhead invention of the present invention; Fig. 6 is a schematic top plan view of a further modified form of the present invention; Fig. 6a is a schematic vertical sectional view of the construction shown in Fig. 6; Fig. 7 is a schematic top plan view of a still _OMP further modified form of the present invention; Fig. 7a is a schematic vertical sectional view of the construction shown in Fig. 7; Fig. 8 is a graph of the static deflection pro- duced in the compound drumhead of Fig. 1 and a uniform drumhead by an applied effective mass; Figs. 9, 10 and 11 show graphs of the ratio squared of the large amplitude resonance frequency to the small amplitude resonance frequency of the compound drumhead of Fig. 1 and a uniform drumhead plotted against the resultant displacement at the center of the drumhead for the fundamental mode of the drum when the only difference is the initial tension applied to the drumhead; and Fig. 12 comprises a family of curves showing the affect of a change in the dimensions of a com¬ pound drumhead on the pitch modulation produced during play of the drum. The improved drum structure in accordance with a preferred embodiment of the present invention comprises a drum with a generally cylindrical body having mounted on at least one end thereof a com¬ pound drumhead which in the form shown in Figs. 1 and 2 comprises a conventional flexible, stretch- resistant uniform drumhead membrane adapted for mounting on a drum and having integrally secured to one surface of the drumhead membrane a ring¬ like section of flexible stretch-resistant material to provide a drumhead having an inner center section or portion having a predetermined average thickness generally of substantially uniform thickness provid¬ ing an area adapted to be struck by drum sticks during play of the drum and an outer section or portion of flexible, stretch-resistant material of increased average thickness generally of substant¬ ially uniform thickness disposed around the center portion, preferably extending from the center por¬ tion outwardly to the outer edge of the drumhead. The outer ring-like section or portion of increased thickness is preferably formed of the same flexible, stretch-resistant material as the uniform drum- head membrane and is securely affixed to the drum¬ head membrane over the entire area thereof by a thin, flexible layer of adhesive material to provide a continuous unitary compound drumhead structure having a portion thereof which increases the resis- tance to stretch when struck by a drumstick without adding a large amount of mass to the drumhead and effecting an undesirable lowering of the normal pitch of the drum. The outer ring-like portion has a width less than the radius of the drumhead and provides a drumhead with an outer section of increased average thickness with a central area preferably of substantial uniform thickness which has an average thickness less than the remainder of the drumhead and provides an area sufficiently large to be struck with drum sticks during normal play. The width of a ring-like outer portion or ring¬ like construction which is adapted to be mounted on a drumhead membrane as described herein can be determined by selecting an outer portion or ring member of a width which produces a pitch change most pleasing to the musician or most suitable OMPI for the type of music being played. Where a maxi¬ mum pitch change is desired, however, the width of a Mylar-type ring member or ring-like construction of the type which extends inwardly from the outer supporting edges of the drumhead formed of Mylar- type drumhead material and having a substantially uniform thickness which should be used to produce the optimum momentary pitch modulation or pitch change can be determined by referring to Fig. 12 of the drawing. Figure 12 shows a family of curves represent¬ ing the ratio squared of the resonance frequency (w) to the natural or small amplitude frequency (wo) of a drumhead plotted against the ratio ID/OD or "0D-2RW/0D" wherein "ID" is the inner diameter or play area of a drumhead membrane, "OD" is the diameter of the drumhead membrane within-the outer supporting edges thereof and "RW" is the width of the ring member, and where the drumhead has 3- radius of .165 meters, a drumhead membrane thick¬ ness of .000254 meters, and a ring thickness rang¬ ing between 0 and .002032 meters in steps of .000254 meters. The resonance frequency at the primary mode of the drum was maintained constant at 80 Hertz (Hz) and the amplitude at the drumhead cente " r was equal to .005 meters. In Fig. 12 the curve No-. 1 was derived using a plain Mylar drumhead having no outer ring member and each of the curves No. 2 through 9 was derived using a Mylar ring member of progressively increasing thickness as indicated which was mounted integrally on the said drumhead membrane. The points of maximum pitch change for each ring thickness are connected by an asymptotic curve (M) . The preferred operat¬ ing range of the ratio of ID (diameter of the cen¬ ter portion of the drumhead) to OD (diameter of the drumhead membrane) is between about 0.3 to 0.9 with the absolute theoretical maximum ratio ap¬ proaching 0.7. As an example of the application of Fig.12 for determining the width of a Mylar ring member which produces the optimum pitch change in a drum having a drumhead membrane outer diameter (OD) of 0.165 meters (13 inches) and with the ring-like section having a thickness of .000254 meters and a stan¬ dard Mylar drumhead membrane having a thickness of .000254 meters, Fig. 12 shows the optimum pitch change will be obtained where the ratio of ID/OD is about 0.46. By solving the equation ID/OD=0.46, it will be evident that the ID of the center por¬ tion is 6.0 inches and the RW (ring width) is 3.5 inches. A Mylar or Mylar-like ring .000254 meters thick having a width of 3.5 inches mounted on the said drumhead membrane provides a momentary pitch increase of about 8 percent. A thicker ring of the same width would provide a greater pitch in¬ crease. It will also be evident from Fig. 12 that in addition to the width of the outer portion or ring¬ like construction having an affect on the momentary change in pitch, the thickness of the ring also has an important affect on the str'etch-resistance and therefore the pitch change produced when the drumhead is struck with a drumstick. In Fig. 12 OMPI it is important to note that the natural resonance frequency of the drumhead was held constant (at 80 Hz) for all of the plotted points. Thus, as the ring added more mass (due to increased thick- ness or width) , the tension was increased from an initial value of 884.54 Newton's/meter to keep the natural frequency of the drumhead constant (at 80Hz) . If the ring member is formed of a material which has a significantly different modulus of elasticity and provides greater resistance to stretch than Mylar or Mylar-like drumhead material, the ring member of the same width and thickness as the Mylar ring section would produce a greater change in pitch. For example, a thin flexible metallic ring, such as metallic aluminum which has about 10 times the resistance to stretch as Mylar, would produce a much greater pitch modulation than the Mylar ring without adding significantly to the mass of the drumhead. Likewise, a thin flexible stainless steel ring or metallic alloy ring would produce a larger change in pitch than the Mylar ring and can be used where special pitch modulations effects are desired. If desired, a compound drumhead embodying the present invention having a relatively thinner inner center section or portion having a predetermined average thickness and an outer section or portion extending radially outwardly therefrom having a greater average thickness can be formed as a unitary, homogenous, structure by molding the drumhead mem¬ brane of a suitable plastic material which is dur- OMPI able, flexible and stretch-resistant to provide the center section preferably having a substantial uniform thickness and an outer ring-like section surrounding the center section which has a substanti- 5 ally uniform greater average thickness. A drumhead having the improved features of the present invention can also be made by forming the outer ring-like section on a conventional drumhead membrane as a liquid coating which on drying forms 10 the outer ring-like section and effects an increase in the average thickness of the outer section of the drumhead membrane without significantly increas¬ ing the mass of the drumheads. A uniform liquid film can be applied to the outer portion of the 15 drumhead membrane, such as by spraying or flowing a liquid flowable material onto a template or by painting. When the liquid material dries, it forms a uniform adherent, unitary stretch-resistant outer section of increased average thickness integral 20 with the drumhead membrane around the central por¬ tion or playing area of the drumhead. A preferred embodiment of the present inven¬ tion is shown in Figs. 1-2 of the drawing where¬ in a drum 10 has a generally circular drumhead 25 11 of substantially uniform thickness formed of durable, flexible drumhead material which is resist¬ ant to stretching when struck with a drum stick, such as Mylar plastic drumhead material, mounted on at least one end of the generally cylindrical 30 body section 12 of the drum with the outer edges of the drumhead membrane held in a conventional fitting 13 provided with tension adjusting screws O 14 which exerts the desired degree of tensioning on the drumhead membrane 11. Secured to the outer surface of the drumhead 11 is a ring-like member 15 formed of a flexible material resistant to stret- ching, such as Mylar plastic or metalized Mylar plastic in sheet form (Mylar is a trademark of E. I. duPont deNemours & Co. and is formed of poly¬ ethylene terephthalate resin) or similar material, which preferably has a uniform thickness of- the same order of magnitude as the drumhead membrane 11 and having a width about half the radius of the drumhead extending inwardly from the outer edge of the drumhead membrane 11. The ring member 15 is secured to the outer surface of the drumhead by a layer of flexible adhesive 17, such as contact cement, so as to securely affix the ring member 15 to the surface of the drumhead 11 and form a unitary structure. Depending on the size of the drum ranging from a diameter of about 6 inches up a typical ring¬ like member 15 can have a width ranging from about 0.02 m to 0.660 m (1 inch to 26 inches), a thick¬ ness between about .0000254 m to .00254 m (1 mil to 100 mil) and in every instance a width less than half the diameter of the drumhead so that the drum can be played in the usual manner without striking the ring-like member. Fig. 3 of the drawing shows a modified form of the improved drumhead structure in which the compound membrane 20 forming the drumhead is a unitary, homogenous structure formed by molding or casting a plastic drumhead material, such as Mylar, so as to form an inner generally circular section 21 having a uniform or substantially uniform thickness and an outer ring-like section 22 having a substantially uniform thickness greater than the thickness of the inner section 21. Fig. 4 shows a further modified form of the invention in which the compound drumhead membrane 30 is formed of a uniformly thick drumhead membrane 31 which has a ring-like member 32 formed on the outer surface thereof which extends inwardly toward a uniformly thin generally circular area 33. The outer ring-like section is formed by applying a layer of liquified drumhead material which when solidified forms a unitary flexible stretch-resistant section of substantially uniform thickness affixed to the surface of the membrane 31 without requiring the use of an adhesive layer to securely attach the ring member to the drumhead membrane 31. As a further modified form of the present inven- tion, the so-called compound drumhead can have the configuration shown in Fig. 5 wherein the drum¬ head 40 is thinnest at the center 41 and progress¬ ively increases in thickness as the distance from the center increases, as at 42. If desired, the center thin portion can be widened to form a ani- formly thin circular portion, at the center of the drumhead as in Figs. 1 and 2 of the drawing with the outer ring-like portion increasing progress¬ ively in thickness as the distance from the center circular portion increases. Figs. 6 and 7 show a generally ring-like construc¬ tion mounted on a drumhead in which portions of OMPI -li¬ the ring construction have been cut out so that there are sections of flexible stretch-resistant material 21, 21a, respectively, disposed about the midpoint of the drumhead 22, 22a, respectively, and formed integrally therewith, preferably symmet¬ rically disposed about the midpoint of the drum 20, 20a, respectively. While the resistance to stretch and the pitch modulation properties imparted to a drumhead by a discontinuous ring-like construc- tion are less pronounced than those provided by a continuous ring member of the same width, there is a significant momentary increase in the pitch pro¬ vided when a drumhead having such construction is struck by drum sticks. EXAMPLE As a specific illustration of the present inven¬ tion, a Ludwig tom-tom having a cylindrical main body section 13 inch in diameter was provided with a standard simple uniformly thick metalized Mylar drumhead membrane for mounting on one end of the torn—torn. A metalized Mylar ring member was adhesively secured by contact cement to the uniform Mylar membrane to form a compound drumhead. The physical constant of the ring member were as follows " : 1.73xl0~4 m = thickness 0.083 m = inner radius 0.165 m = outer radius 1.30x10- kg/m 3 = volume density 0.3 - Poisson's ratio 1.93x10^ N/m 2 = modulus of elasticity f O PI λ The compound drumhead was mounted on the Ludwig tom-tom and a uniform tension applied at six points uniformly spaced around the circumference of the drum. The tension was adjusted to a constant value and the drum was deflected by applying an effective mass (me) so as to effect a static displacement (y) at the center of the uniform membrane. A graph of the static deflection (y) versus the applied effective mass (m ) for the drumhead of the foregoing Example having the ring member attached and also for the uniform drumhead (i.e. the said drumhead membrane with no ring member attached) is shown in Figure 8. Each drumhead initially was under static tension (T ) of 468 N/m. As the applied effective mass (m ). is increas¬ ed, the tension is increased in both drumheads. This is indicated by the decreasing slope in each curve. However, the slope of the curve for the compound drumhead decreases more. rapidly than the slope for the plain drumhead, indicating a higher return force for the same amount of deflection. This indicates that for both membranes driven in the steady state at equal amplitudes, there is a higher return force acting in the compound drum- head hence, a larger increase in frequency is pro¬ duced in the compound drumhead. Fig. 9 of the drawing shows the ratio squared of the large amplitude resonance frequency to the 2 small amplitude resonance frequency (ω/ω 0 ) of the compound drumhead of the Example plotted against the resultant amplitude (η 0 ) at the center of the drumhead for the fundamental mode of the drum where - ϊ E OM the initial tension on the drumhead (force per unit length of circumference) was 351 N/m. Figure 9 also shows a plot of the results obtained when a..drumhead having a uniform membrane identical to that used to form the compound drumhead of the Example was subjected to the same tests under the same tension. Figures 10 and 11 generally show the test re¬ sults obtained when the same compound drumhead and. uniform drumhead of Fig. 9 were subjected to the analysis as in Fig. 9 while under a tension of 468N/m and 752N/m, respectively. The foregoing Figures 9, 10 and 11 show (1) that the compound drumhead membrane provides a greater increase in the resonance frequency or change of pitch when displaced as compared with that of a uniform membrane subjected to a like displacement, and (2) that there is greater change in pitch effected when the tension applied to the compound membrane is relatively low. In the disclosure and/or claims the term "com¬ pound" when used in conjunction with drumhead or membrane designates a drumhead or membrane having distinct portions or sections of different thick- ness and does not require that the drumhead" have two separate parts which are combined to form the dr mhead. It should also be understood that the drumhead of the present invention can have the ring-like section or portion secured to or extending inwardly -14- from the inner surface of the drumhead, the im¬ proved drumhead of the present invention can also be mounted on both ends of an open ended main body section of a drum. When the "outer diameter" of a drumhead membrane is referred to herein or in the claims, it should be understood that the phrase refers to the widest portion of a circular membrane extending inwardly between the supporting edges of the drumhead and does not include those portions of the drumhead membrane which are in contact with the support ring or drum body. While the invention has been described in con¬ nection with drums and drumhead membranes , it should be understood that the invention is equally applicable to other percussion type musical in¬ struments, such as the tympani.

Claims: CLAIMS : 1. A pitch modulator for a drumhead comprising, a generally flat ring-like con¬ struction of flexible stretch-resistant material adapted for mounting concentrically on a circular surface of a drumhead membrane, ■ said ring-like construction having one flat side thereof provided with a coating of adhesive material which when mounted on a surface of the drumhead membrane unites said ring-like construction and drumhead membrane forming a unitary flexible stretch- resistant structure, and said ring-like construction adapted to form said unitary structure with an appreciable portion of the surface of a said drumhead membrane while leaving an unobstructed play area at the center of the drumhead membrane. 2. A pitch modulator as in Claim 1, wherein said ring-like construction has a uniform thick- ness throughout. 3. A pitch modulator as in Claim 1, wherein said ring-like construction has a gradually increasing thickness as the distance from the innermost edge increases. 4. A pitch modulator as in Claim 1, wherein said ring-like construction has a width about half the radius of the outer diameter of said ring-like construction. 5. A pitch modulator as in Claim 1, wherein said ring-like construction has a thickness between about .0000254 meters and .00254 meters. 6. A pitch modulator as in Claim 1, wherein said ring-like construction is adapted to be mounted concentrically on said drumhead membrane from a point adjacent the outer diameter of said drumhead membrane and extend inwardly therefrom. 7. A pitch modulator as in Claim 1, wherein said ring-like construction is formed of the same drumhead material as the drumhead membrane 0 on which the ring-like construction is to be mounted. 8. A pitch modular as in Claim 1, wherein the ring-like construction is formed of flexible metallic sheet material. 5 9. A pitch modulator as in Claim 1, wherein the ring-like construction is formed of plastic drumhead material. 10. A pitch modulator as in Claim 1 , wherein said plastic is comprised -of polyethylene tere- o phthalate resin. 11. A pitch modulator as in Claim 1, wherein said ring-like construction is a flat ring section comprised of polyethylene terephthalate plastic drumhead material for mounting on a 5 drumhead membrane formed of the same drumhead material, and said ring-like construction having a predetermined outer diameter "OD" has a width "RW" within a range of a maximum width determin¬ ed by the equation OD-2RW/OD=0.3 and a minimum 0 width determined by the equation OD-2RW/OD = 0.9. OMPI 12. A pitch modulator as in Claim 1, wherein said ring-like construction has a thickness and width indicated by the curve M of Fig. 12 of the drawing. 13. A drumhead adapted for mounting on a generally cylindrical drum body section com¬ prising a generally circular drumhead membrane of durable flexible stretch-resistant material having a center circular portion of predetermin- ed average thickness comprising the area which is struck by drumsticks during normal play of the drum and an outer ring-like construction which extends appreciably over the surface of the drumhead membrane surrounding said area, said outer ring-like construction being formed of flexible stretch resistant material forming with said center portion a continuous unitary drumhead membrane structure and providing an outer portion having a greater average thick- ness than said center portion. 14. A drumhead as in Claim 13, wherein said drumhead membrane and ring-like construc¬ tion having an outer diameter "OD" are compris¬ ed of polyethylene terephthalate plastic drum- head material and said ring-like construction has a width "RW" within a range of a maximum width determined by the equation 0D-2RW/0D = 0.3 and a minimum width determined by the equation OD-2RS/OD = 0.9. 15. A drumhead as in Claim 13, wherein said ring-like construction has a width indica¬ ted by the curve of Fig. 12 of the drawing. OMPI 16. A drum structure comprising a generally cylindrical body section having mounted on at least one end thereof a drumhead comprising a generally circular drumhead membrane of dur- 5 able flexible stretch-resistant material having a center circular portion of a predetermined average thickness comprising an area which is struck by drumsticks during normal play of the drum and an outer ring-like construction 10 which extends appreciably over the surface of the drumhead membrane surrounding said area, said ring-like construction being formed of flexible stretch resistant material and toget¬ her with said drumhead membrane providing an 15 outer portion having a greater average thick¬ ness than the average thickness of said center portion and said outer portion forming with said center portion a continuous unitary drum¬ head membrane structure; whereby a large oment- 20 ary increase in the pitch of the drum is effec¬ ted when said center portion of the drumhead membrane is struck a sharp blow with a drum stick and simultaneously decreasing the decay time in which the drumhead membrane returns 25 to rest after being struck a sharp blow compar¬ ed with a uniformly thick drumhead membrane of said predetermined average thickness. 17. A drum structure as in Claim 16, where¬ in said outer ring-like construction is compris- 30 ed of a flat thin ring section of substantially uniform thickness adhesively secured to a sur¬ face of said drumhead membrane. 18. A drum structure as in Claim 16, where¬ in said ring-like construction is integral with said drumhead membrane. 19. A drum structure as in Claim 16, where- by said ring-like construction extends from the outer edge of said center circular portion outwardly to about said cylindrical body section. 20. A drum structure as in Claim 16, where¬ in said center portion and said ring-like con- struction of said drumhead membrane are compris¬ ed of polyethylene terephthalate resin. 21. A drum structure as in Claim 16, where¬ in said drumhead membrane and ring-like cons¬ truction having an outer diameter "OD" are comprised of polyethylene terephthalate plastic drumhead material and said ring-like construc¬ tion has a width "RW" within a range of maximum width determined by the equation 0D-2RW/0D = 0.3 and minimum width determined by the equa- tion 0D-2RW/0D = 0.9. 22. A drum structure as in Claim 16, where¬ in said ring-like construction has a width indicated by the curve M of Fig. 12 of the drawing. 23. A method of momentarily increasing the pitch of a drum when the drumhead is struck with a drumstick during play which comprises; integrally securing concentrically on a circu¬ lar surface of a drumhead membrane a flat ring- like construction of flexible stretch-resistant material, said ring-like construction forming _ OMPI a unitary stretch-resistant structure with an appreciable portion of said surface of the drumhead membrane while leaving an unobstructed play area at the center of the drumhead. 24. A method as in Claim 23, wherein said drumhead membrane and said ring-like construc¬ tion having an outer diameter "OD" are compris¬ ed of polyethylene terephthalate plastic drum¬ head material and said ring-like construction has a width "RW" within a range of a maximum width determined by the equation 0D-2RW/0D = 0.3 and a minimum width determined by the equation 0D-2RW/0D = 0.9. 25. A method as in Claim 23, wherein said ring-like construction has a width indicated by the curve M of Fig. 12 of the drawing. f v O

Inventors: ROSE C
Applicants: ROSE C
Application year: 1980
Main classification: G10D13
IPC codes: G10D13