US1767678A - Sounding board - Google Patents

Description

June 24, 1930. M. R. HUTCHISON 1,767,678

SOUNDING BOARD Filed April 1, 1927 INVENTOR fl/l'ller Reese Hate/viso 742 BYQI- ATTORNE\ Patented June 24, 1930 UNITED STATES PATENT OFFICE MILLER REESE HUTCHISON, OF WEST ORANGE, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO ACOUSTIC PRODUCTS COMPANY, OF NEW PORATION OF DELAWARE YORK, N. Y., A COR- SOUNDIN G BOARD Application filed April 1, 1927. Serial No. 180,182.

This invention relates to new and useful improvements in sounding boards and methods of tuning and its object is to provide simple means for tuning sounding boards to change their responsiveness to sound waves of different frequencies. It is well known that the periods of vibrations of drumheads, strings and the like can be changed by stretching or applying tension thereto and the more speci 0 object of the present invention is to apply this same principle to sounding boards.

Obviously this may be done in several ways and for the purpose of so describing my invention that it will be readily understood by those skilled in the art, I will illustrate and describe a few simple embodiments of it, without, however, limiting m self to any specific arrangement. In fact intend no limitations other than those imposed by the appended claims. By sounding board I mean a vibratory member preferably formed of wood or other fibrous material having a natural free period of vibration which is either adapted to reflect or to create sound waves.

Referring to the drawings,

Fig. 1 is a sectional plan of a sounding board which embodies this invention;

Fig. 2 is a side elevation of the structure shown in Fig. 1;

Fig. 3 is a plan view of a flat sounding board which is to be put under tensionwithout material flexing;

Fig. 4 is a side elevation of such a board as is shown in Fig. 3, with associated parts for putting it under tension;

Figs. 5 and 6 are a plan and elevation of across its center. 12 and 13 are stiff reinforcing pieces across opposite ends of the board which are either integral parts of the board or are rigidly afiixed to it. 14 and 15 are oppositely threaded rods running through the pieces 12' and 13 and adjustably engaged by a nut 16 which forms with them a turn-buckle.

By means of the turn-buckle the board may be bowed as shown and to a greater or less extent as desired. Increasing the tension on the rods 14 and 15 and the consequent increase in the flexure of the board and its rib, makes the combination responsive to sound waves of higher frequencies. So permitting the board and its rib by their inherent resiliency, to assume a position more nearly plane, will make the device responsive to sound waves of a lower register.

Another way of accomplishing the desired result is to stretch the sounding board by some such arrangement as those shown in Figs. 3 to 6.

In Figs. 3 and 4, 20 is a sounding board with a longitudinal rib 21 which extends slightly beyond its ends. A link 22 is connected at one end to an anchorage 23, and at its other end to the rib 21, by means of a pin 24 which passes through it and through the rib. 25 is a turn-buckle which adjustably connects the other end of rib 21 with another anchorage 26.

By means of this arrangement the board may be stretched a desired amount to make it responsive to a desired range of sound wave frequencies.

A sounding board without a projecting rib, such as that shown in Figs. 1 and 2, or without any rib may be stretched similarly. Figs. 5 and 6 show a board 30 without a longitudinal rib but with stiff reinforcing pieces 31 and 32 across its ends which may be either integral parts of the board or independent pieces rigidly affixed to it. The link 22 is connected to the piece 31 and the turn-buckle 25 to the piece 32. The mode of operation is obvious.

The desired tension of the sounding board may be obtained by torsion. An untwisted board 40, with reinforcing pieces across its ends, is shown in plan view in Fig. 7. Figs. 8 and 9, which illustrate the board twisted out of a pla e, show the upper reinforcing pieces designated by reference numeral a1 and the lower ones by 4-2. These have been moved against the resiliency of the board, out of parallelism as viewed from the top, to put the board 40 under tension. The board is flexed throughout but to the greatest extQ'lt at the part thereof midway between the end reinforcements. The distance between the reinforcements all and i2 is changed somewhat by varying their relative angularity.

The fundamental note of this board is changed by varying the angularity between its upper and lower edges.

Although the several methods described herein tend to make the sounding board so stressed more responsive to one particular frequency, the primary advantage of my present stem lies in the tact that a certain tension applied to the board will make it equally responsive to a wide range oi. the quencies.

hat I claim is:

2. A resilient soui'iding board. means for stillicning spaced portions thereof and means for changing the natural relative position of said stillencd portions.

2. A resilient counding board, means for stiffening opposite ends thereof and means for changing the natural relative position of said stiit'ened ends.

3. A resilient sounding board. means for stiflcning opposite ends thereof and means for changing; the natural relative distance between said stitl'ened ends.

4:. In a resilient sounding board formed of fibrous material. musically inert means for varying the longitudinal tension of the board to render said board responsive to a pinrality of sound wave frequencies.

A resilient sounding board normally responsive to a plurality of sound wave frequencies, including means for varying the longitudal and transverse tension of the board whereby to render said board responsive to an increased degree to a specific band of frequencies.

6. A resilient sounding board normally responsive to a plurality of frequencies including means for varying the longitudinal and transverse tension of the board to render said board responsive to an increased degree to a predetermined band of frequent: lying within the range of said first-named plurality of "frequencies.

In witness whereof, I have hereunto set my hand this 30th day of March. 1927.

ZillLLlilt REESE HUTCHISON.

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