Perceptual speech quality improvement for vocoder based on amplitude spectrum of residual signal

In this paper, we propose a linear pre- and post-filter for improving the perceptual speech quality of a vocoder based on amplitude spectrum of residual signal. The goal of the pre-filter in analyzer is to make the noise of spectrum inaudible. It attempts to hide the noise under the signal spectrum by exploiting human auditory masking. The post-filter in synthesizer is to improve speech quality. Experimental results show that the proposed vocoder can obtain an average mean opinion score (MOS) of 4.5 for four voices (2 female and 2 male voices) while preserving high-quality property after parameter compression.