A pseudo-cepstrum based short-term postfilter

Abstract

We propose an adaptive short-term postfilter for speech coders by incorporating the properties of the pseudo-cepstrum. Since the proposed postfilter implicitly has a characteristic of tilt compensation, it does not require an additional tilt compensation filter as conventional techniques. We derive a relationship between the parameters of the proposed postfilter based on a minimum phase distortion criterion, and show a simple tuning procedure for the parameters. It is also shown that the postfilter can be implemented with a lower order. By applying this postfilter to several international speech coding standards, we reduce the complexity of the speech coders while obtaining comparable performance to conventional approaches.