Literature Review

Abstract

This chapter first introduces the transmission channels employed currently for speech communication and their main impairments and then presents the literature review, divided into three parts: channel quality evaluation, human speaker recognition, and automatic speaker recognition. Different procedures for evaluation and main outcomes relevant to this work are indicated. The review of channel quality evaluation reports the current status of investigations addressing subjective perceptions and automatic evaluations of signal quality when the speech is transmitted through different kinds of communication channels. The rest of this review shows state-of-the-art methods to assess the human and the automatic speaker recognition performances, and the channel impairment effects that have been reported in previous investigations. On the human side, pertinent listening tests to assess the human capability to detect speaker identities reveal how the performance is influenced by different voice distortions. On the automatic side, a review of the most recent and efficient methods for automatic speaker recognition and their main findings under channel degradations are presented. Based on the fact that channels of extended bandwidths generally offer better quality and on the assessed importance of different speech frequency ranges for speaker recognition, this book concentrates on evaluating the advantages of enhanced channels for the human and for the automatic speaker recognition performance, clarifying how transmissions affect the speaker-specific voice properties and their relation to signal quality measurements.