Voice modification system

Claim 1

Apparatus for modifying an applied voice signal to produce any one of a plurality of modified voice sounds, each of which has a unique understandable voice sound different from that which would result from the applied voice signal, comprising: a plurality of band pass filters having mutually exclusive, collectively exhaustive, octavely related pass bands, each band pass filter being responsive to the applied voice signal for producing a respective one of a plurality of voice signal components having mutually exclusive, collectively exhaustive, octavely related frequency bands; a frequency generator for producing a plurality of output signals having geometrically related frequencies all of which are higher than the highest frequency passed by the band pass filters, one of which is a basic reference frequency; means responsive to the basic reference frequency output signal for producing a plurality of reference signals, each having frequency which is octavely related to the basic reference frequency; a modulator associated with each of the band pass filters for modulating an applied respective one of the reference signals with the voice signal component produced by the associated band pass filter, the applied reference signal having frequency substantially higher than the associated frequency band, the voice signal component and the reference signal applied to each modulator having the same proportional frequency relationship; a low pass filter associated with each of the modulators for substantially attenuating the upper sideband of the voice modulated signal component produced by that modulator; a demodulator associated with each of the low pass filters for demodulating the filtered voice modulated signal component produced by the associated filter with an applied demodulating signal having frequency which is shifted relative to the associated reference signal frequency to produce a corresponding shift in the frequency of the associated voice signal component; switching means associated with each of the demodulators for selecting any one of a plurality of the frequency generator output signals; means responsive to the frequency generator output signal selected by each of the switching means for producing an output signal having the same octave frequency relationship to the associated switching means output signal as the associated reference frequency has to the basic reference frequency and for applying that output signal to the associated demodulator as the applied demodulating signal; a low pass filter associated with each of the demodulators for substantially attenuating the components of the demodulator output signal having frequency higher than the base band component of the demodulator output signal; a signal combining network for combining the demodulated voice signal components to produce a modified voice signal; and an audio transducer for rendering the modified voice signal audible.