On peculiarities of evaluating the quality of speech and music signals subjected to phase distortion

In this paper, subjective and objective estimators of the quality of speech and music signals subjected to phase distortion are compared, and mapping between objective and subjective quality estimates is realized. It was found that the phase distortion of speech signals is perceived stronger than ones for musical signals. Two types of phase distortion are considered: 1) low-frequency signal components lag behind high-frequency components in the 30–90 ms; 2) high-frequency signal components lag behind low frequency components in the same time. It is shown that the human auditory system is more sensitive to the latter type of phase distortion referenced previously. As far as objective quality measures, it was found they are useless for distinguishing these types of phase distortion. Maximum differences between group delay times for low (125 Hz) and high (8 kHz) frequencies, for which distortion is acceptable, were established. These threshold values are 40 ms for speech and 80 ms for music.