Single Channel Phase-Aware Signal Processing in Speech Communication

Chapter 6Phase-Aware Speech Quality Estimation

Pejman Mowlaee

Graz University of Technology, Graz, Austria

6.1 Chapter Organization

While various studies have been conducted on evaluating and analyzing the correlation of instrumental measures with subjective listening tests, the importance of phase in speech quality estimation has not been adequately studied. Therefore, in this chapter we address the importance of phase in speech quality estimation, in particular when the spectral phase of the signal is modified. Through several examples, we will show how the conventional instrumental measures are limited to the assessment of magnitude-only modification schemes.

As the conventional measures mostly rely on the distortion metrics applied to the spectral magnitude of a reference (desired) signal and the estimated (processed) signal, it is not clear how reliable the conventional measures are when used to predict the performance of a phase-aware speech processing application (for two examples, see Chapters 4 and 5). Therefore, we seek to address the following two fundamental questions:

• How well do the conventional instrumental measures predict the performance of signal enhancement methods where both spectral amplitude and phase are modified?
• Is it possible to improve the reliability of the speech quality prediction by considering new measures?

In this chapter, to address the first question we will present a correlation analysis between conventional instrumental measures and subjective ...