Noise suppression using a time-varying, analysis/synthesis gamma chirp filterbank

Spectral subtraction has been cited most often as a noise suppression method for speech signals in steady background noise, because it is basically a non-parametric method and simple enough to implement for various applications using FFT. It has also been well known, however, that spectral subtraction produces so called "musical noise" in synthetic sounds. Since such musical noise, even at low levels, can often bother humans in speech perception, spectral subtraction has not been very successful in signal processing applications for human listeners. To suppress noise without producing musical noise, an alternative method has been developed using a time-varying, analysis/synthesis gammachirp filterbank; this was initially proposed as an auditory filterbank. The present method achieves about the same SNR improvement as spectral subtraction when using the same information on the non-speech interval. Moreover, the synthetic sounds only contain steady white-like noise at reduced levels when the original noise is white. This method is, therefore, advantageous in various applications for human listeners.