4 •71,746

43J•5.Hp AUTOMATIC MUSICAL TUNING DEVICE

John G. Dobbie, New South Wales 2070, Australia 9 June 1981 (Class 84/454); fried in Australia 12 July 1977 "An electronic automatic musical tuning device whereby an in-

coming tone from a musical instrument is picked up by a micro- phone, amplified and transformed to a square wave signal and com- pared in a phase locked loop with a progressive series of standard frequencies until matching occurs and the loop is locked to enable a display of the tone in a convenient output such as a row of lights." -DWM

4,281,577

43.85.Hp ELECTRONIC TUNING DEVICE

Peter Middleton, De Kalb, Illinois 60115 4 August 1981 (Class 84/454); f'ded 21 May 1979

In the first of four possible modes of operation, this device will sound, for direct audible comparison with an unknown note played on an instrument to be tuned, a note that has been selected manual- ly by pressing one of seven octave buttons and one of 12 chromatic note buttons. In the second mode, the frequency selected manually by the octave and chromatic buttons is compared electrically with the frequency of the note played on the instrument; there is a beat- frequency indicator that consists of a cluster of four light-emitting diodes (LED); if the light pattern thereon rotates clockwise the un- known note is sharper than standard; the rate of rotation is an indi- cation of how great the mistuning. In the third mode, the device tracks the unknown note and sounds the standard note nearest to the unknown for audible comparison. In the fourth mode, the un- known is tracked in frequency to the nearest standard, and the dif- ference frequency is indicated by the direction and rate of rotation of the pattern of the beat-frequency indicator. An unusual feature of this tuning device is that the standard frequencies can be selected from: usual equal temperament, equal temperament with three types of stretch, Werckmeister III, Kimberger III, Silbermann 1/6 comma, van Biezer 1/4 meantone, Pythagorean, just, or Rameau modified 1/4 comma. The standard frequencies are obtained by divisions of 40 MHz; the divisors are not disclosed explicitly in the patent.-RWY

4,276,449

43.88.Ar SPEAKER OR MICROPHONE HAVING CORRUGATED DIAPHRAGM WITH CONDUCTORS THEREON

Tadashi $awafuji, Tokyo, Japan 30 June 1981 (Class 179/115.5 PV); f'ded in Japan 1 June

1978

This Blatthaller-type loudspeaker has at least two novel features. First, the diaphragm assembly is formed by corrugating a flat plate after the meandering voice coil has been affixed. Second, a double

bellows suspension allows substantial diaphragm excursion while providing well controlled centering.-GLA

4,276,443

43.88.Ar SOUND REPRODUCING SYSTEM UTILIZING FEEDBACK AND VELOCITY-FREQUENCY

EQUALIZATION

Stanley T. Meyers, Red Bank, New Jersey 07701 30 June 1981 (Class 179/1 F); •ed 17 August 1979

This motional feedback loudspeaker system has already been granted U.S. Patent 4,256,923, reviewed previously [J. Acoust. Soc. Am. 70, 1208 (1981)]. This newer patent gives a more detailed de- scription of how desired acoustic response can be approached by in- cluding suitable equalization in the electrical feedback loop.-GLA

4,276,446

43.88.Ja ACOUSTIC TRANSDUCER SYSTEM

Anthony R. Taddeo, Rochester, New York 14610 30 June 1981 (Class 179/1 E); f'ded 5 October 1979

The reviewer used to think that it should be possible to get more extended and smoother low-frequency response by simultaneously driving several ported systems tuned to different resonance frequen- cies. Now one would assume that such a notion had been put to rest for once and for all by the general awareness of the work of Thiele and Small. Such is apparently not the case. The patent in question specifies passive radiators rather than ports in three stagger- tuned enclosures.-G LA

4,280,585

43,88.Ja MULTI-SOUND SPEAKER SYSTEM

Motoyoshi Nakanishi, Honcho, Japan 28 July 1981 (Class 181/147); filed in Japan 27 August 1979 Several wide-range loudspeakers are mounted in a magical

ported enclosure which "guides" back pressure through a W-shaped labyrinth having adjustable flappers at its exits. "... an ideal fre- quency characteristic is efficiently obtained .... optimum direction- al sound radiation pattern compatible with various listening environ- ments... reduction in intermodulation distortion... high resolving power and dynamic sound characteristics," and more of the same. -GLA

4,281,738

43.88.Ja SPHERICAL LOUDSPEAKER ENCLOSURE

Michael Jackson, Phoenix, Arizona 85018 4 August 1981 (Class 181/151); fried 26 December 1979

A loudspeaker enclosure is made of molded, closed-cell poly- urethane foam. The interior is spherical. How large should the in- terior volume be? Apparently no one has successfully answered this question before, so the patent includes a new formula: take the maximum peak-to-peak excursion of the loudspeaker to be used, multiply that figure by the diameter of the speaker, and cube the result. Not only does this optimum-volume spherical back-chamber eliminate distortion and increase power handling, it also provides greater efficiency than a more conventional acoustic suspension de- sign. Ah well, right you are if you think you are.-GLA

1817 J. Acoust. Soc. Am. 70(6), Dec. 1981; 0001-4966/81/121817-01500.80; ¸ 1981 Acoust. Soc. Am.; Patent Reviews 1817

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