Performance evaluation of analysis-by-synthesis homomorphic vocoders

Previous research has shown that the homomorphic filtering procedure combined with analysis-by-synthesis excitation coding is a promising alternative to linear predictive coding (LPC) for low bit rate vocoding. In particular, static vector excited and dynamic vector excited homomorphic vocoders have been designed. In this work, the performances of recently developed homomorphic vocoders are evaluated through formal subjective listening tests, using a variation of the paired acceptability rating method. The subjective test results show that the vocoder framework using analysis-by-synthesis excitation analysis is capable of producing good speech quality at 4.8 kb/s or lower