Patent ID: 8019086

Claim:
A method of synthesizing stereo sound from a monaural sound signal comprising the steps of: low pass filtering the monaural sound signal; producing first and second decorrelated low pass filtered signals; producing respective first and second low pass intra-aural difference signals from said first and second decorrelated low pass filtered signals; band pass filtering the monaural sound signal; high pass filtering the monaural sound signal; producing first and second decorrelated high pass filtered signals; said steps of producing first and second decorrelated low pass filtered signals and producing first and second decorrelated high pass filtered signals each include filtering an input with respective first and second complementary comb filters, wherein frequency peaks of said first comb filter matches frequency notches of said second comb filter and frequency notches of said first comb filter matches frequency peaks of said second comb filter, where said first comb filter C 0 is calculated by: C 0 =(1 +αz D )/(1+α) said second comb filter C 1 is calculated by: C 1 =(1 −αz D )/(1+α) where: C 0 is the first comb filter output; C 1 is the second comb filter output; D is a delay factor; α is a scaling factor; and z is the input signal; producing respective first and second high pass intra-aural difference signals from said first and second decorrelated high pass filtered signals; summing said first low pass intra-aural difference signal, said band pass signal and said second high pass intra-aural difference signal to produce a first stereo output signal; and summing said second low pass intra-aural difference signal, said band pass signal and said first high pass intra-aural difference signal to produce a second stereo output signal.