Objective estimation of perceived speech quality .II. Evaluation of the measuring normalizing block technique

For pt.I see ibid., vol.7, no.4, p.371-82. Part I of this paper describes a new approach to the objective estimation of perceived speech quality. This new approach uses a simple but effective perceptual transformation and a distance measure that consists of a hierarchy of measuring normalizing blocks. Each measuring normalizing block integrates two perceptually transformed signals over some time or frequency interval to determine the average difference across that interval. This difference is then normalized out of one signal, and is further processed to generate one or more measurements. In this part, the resulting estimates of the perceived speech quality are correlated with the results of nine subjective listening tests. Together, these tests include 219 4 kHz bandwidth speech codecs, transmission systems, and reference conditions, with bit rates ranging from 2.4 to 61 kb/s. When compared with six other estimators, significant improvements are seen in many cases, particularly at lower bit rates, and when bit errors or frame erasures are present. These hierarchical structures of measuring normalizing blocks, or other structures of measuring normalizing blocks may also address open issues in perceived audio quality estimation, layered speech or audio coding, automatic speech or speaker recognition, audio signal enhancement, and other areas.