Speech enhancement system for hands-free telephone based on the psychoacoustically motivated filter bank with allpass frequency transformation #

In this paper the application of multirate acoustic echo canceller derived from cochlea model and psychoacustically motivated noise and residual echo attenuation system operating on the signal decomposed in cochlear spaced subbands are described. Polyphase realisation of the FIR filter bank with non-uniform frequency resolution achieved by the frequency transformation of filter characteristic using recursive allpasses is presented as a starting point to construct of the analysis and synthesis filter bank used in proposed speech enhancement system. Human auditory perception model delivered by the psychoacoustic as well cochlear model with discrete time and discrete space are used to create this allpass transformation filter bank. Performing the acoustic echo cancellation by adaptive filtering in subbands we get echo compensated signal, which is forwarded to the noise and residual echo suppression unit. Presented idea of the system combines frequency warping and acoustic echo and noise control techniques to serve in application of communication hands-free device.