Abstract: A method of (and apparatus for) extending the useful dynamic range of an audio reproduction system. An input acoustic signal in the audible range is transduced to form an analog electric signal which is amplified along parallel paths to gain levels g.sub.1 and g.sub.2 (where g.sub.2 >g.sub.1), the amplified signals being sampled to provide two binary digital signals. The analog signal consists of a high amplitude portion and a low amplitude portion. The two binary digital signals are processed by a computer which provides a first binary output and a second binary output, the first binary output being a digital representation of the sequential samples of the audio signal taken at the respective gain setting g.sub.1 or g.sub.2. More precisely, the first binary digital output is a composite binary digital waveform consisting of a high amplitude portion at gain setting g.sub.1, a low amplitude portion at gain setting g.sub.2 and a transition or cross-fade portion therebetween.

Abstract: A pulse generator for outputting a train of electric pulses with a controllably constant period (i.e., the reciprocal of pulse rate) between pulses of the pulse train. The generator includes electrical circuitry which produces an internal train of pulses some of whose periods vary an unacceptable amount from one another. Further, modifying circuitry is connected to receive each pulse of the internal train of pulses, the further circuitry being operable to modify the period of each pulse, when necessary, to an acceptable period with respect to the immediately preceding pulse.

Abstract: A method of (and apparatus for) extracting the fundamental pitch period of a complex electrical signal V.sub.2 (t), that includes the serial steps of deriving a time varying reference signal V.sub.ref (t) from the complex electrical signal V.sub.2 (t), which reference signal V.sub.ref (t) adapts continuously (i.e., each cycle of the complex electrical signal) to peak amplitude excursions of the complex electrical signal V.sub.2 (t); sensing ascending values of the signal V.sub.2 (t) to a first point at which the maximum magnitude of the signal V.sub.2 (t) of one polarity is reached and reversal of direction thereof occurs; storing the first substantially instantaneous difference in magnitude between the complex electrical signal V.sub.2 (t) and the time varying reference V.sub.ref (t) at the point of maximum magnitude of the signal V.sub.2 (t); thereafter sensing a point at which the magnitude of the signal V.sub.

Abstract: Apparatus and method for generating complex sounds having a more natural and agreeable quality wherein fundamental and higher order components may be uniquely and independently controlled to inexact integer relationships.