Speech recognition using an auditory model with pitch-synchronous analysis

An auditory model with two-tone suppression has previously been shown to perform better in speech recognition experiments than a conventional filterbank representation, particularly with noisy or distorted speech. It was, however, known to have several defects including an uneven response across the spectrum and a tendency to detect harmonics of F 0 rather than F 1 . We show that instants of glottal excitation can be derived from the model even with noisy speech. By using this information to carry out pitch-synchronous analysis in a slightly modified model the problem of interaction with harmonics of F 0 can be solved. An analysis of the behavior of the model leads to a specification of a class of processes showing two-tone suppression and hence to a redesigned model avoiding the known defects. The pitch-synchronous analysis is then no longer necessary, but the robust indication of excitation points may have other uses. Spectrograms from the old and new models illustrate the improvements obtained.