Abstract: An audio signal processing system for producing a moving comb filter effect having an all pass phase filter or other suitable phase shifting device in a first input branch and a bypass circuit with an optional inverter in a second input branch. A frequency shifter is inserted either into the first or the second input branch. A first summing network is connected to the outputs of the first and second input branch. An optional second summing network is connected to the output of the first input branch and the inverted output of the second input branch. A feedback circuit may be connected between the output of one of the summing networks to the input of the system to enhance the moving comb filter effect. Also, at least one switching circuit may be used to obtain phase reversals in the frequency shifter thereby facilitating up or down detuning or successive up and down detunings of the comb filter frequencies.

Abstract: A system for extracting the fundamental frequency or pitch of complex waves such as voice, musical instruments or other audio signals. Separate channels extract the fundamental frequency component when it is present in successively wider frequency bands, the frequency intervals between which are equal or less than an octave. Control signals generated in response to the presence of the fundamental components in any lower frequency channel inhibit each of the higher frequency channels thereby reducing the possibility of an overtone being detected as a fundamental frequency component of the complex wave.

Abstract: Described herein are analog speech encoder and decoder systems using a plurality of narrow band pass filters with associated rectifiers and ripple filters for spectrum analyzing the speech or other suitable signals, and a corresponding plurality of narrow band pass filters with associated voltage controlled amplifiers for remaking the speech with either an injected carrier or a noise signal being applied to the voltage controlled amplifier inputs, said carrier or noise source signals being selected by a voice controlled circuit, activating the carrier in the presence of voiced sounds or vowels, and the noise source in the presence of unvoiced sounds or consonants; said innovations or the combination thereof consisting of (1) the use of a direct bypass for the high speech frequencies from the voice input to the decoder output, using a high pass filter essentially passing the unvoiced speech sounds, (2) the limitation of the bandpass filter range of the encoder and decoder sections to the cut-off frequency of t

Abstract: This invention deals with significant innovations on multiphase signal oscillators including quadrature oscillators for the use in frequency shifters, or sequential gating devices for special multichannel sound effects, or three-phase power sources or other electronic apparatus.