Perceptual phase redundancy in speech

For efficient quantization of speech representation, it is common to incorporate perceptual characteristics of human hearing. However, the focus has been confined only to the magnitude information of speech, and little attention has been paid to phase information. This paper presents a novel approach, termed perceptually irrelevant phase elimination (PIPE), to find out irrelevant phase information of acoustic signals in terms of perception. The proposed method, which is based on the observation that the relative phase relationship within a critical band is perceptually important, is derived not only for stationary Fourier signal but also for harmonic signal. The proposed method is then incorporated into the analysis-by-synthesis system based on harmonic representation of speech, and subjective test results demonstrate its effectiveness