Abstract: An acoustic signal generator circuit produces electrical acoustic signals ose frequency spectrum and envelop curve respectively determine the acoustic parameters, pitch and timbre and, respectively, the change in amplitude with time and accordingly the volume, attack and decay phenomena and also quasi stationary behavior of the corresponding sound. There is a manually actuated control device for influencing at least one part of the acoustic parameters. The control device can be constructed in a manner similar to an accordion with a blow bellows and at least one keyboard.

Abstract: The specification describes the restoration of old sound recordings. Old ordings, e.g. phonograph records or tape recordings having at least one substantial musical part such as a singing voice, a solo-instrument or the like, with a formant character, are restored by playing back with the production of an electrical acoustic signal. The amplitude of the acoustic signal is enhanced in frequency ranges which correspond to the formants of the significant musical part.

Abstract: Method and apparatus for synthesis or imitation of sounds of musical instents wherein the partial tone structure is a function of the volume or intensity impression to be effected with a listener, and controlled by controlling the relative content of signal contribution in the overall signal of component signals in such a manner that the timbre of the resulting sound will simulate that of softly played (piano) or loudly played (forte) sound; in a system, signal sources representing the signal components are relatively mixed, for example by a control volume control, and applied to an amplifier; or a signal now U.S. Pat. No. 4,064,482, Maisch et al. source generating a composite signal including all components is connected to a plurality of filters and subsequently connected amplifiers of controllable pass frequency and damping (amplification) characteristic to synthesize the timbre of piano, or forte music regardless of actual volume of output.