Evaluation of a segmental SNR measure as an indicator of the quality of ADPCM coded speech

Two objective measures of speech quality, the traditional signal to quantization noise ratio (SNR) and a segmental SNR, are compared from the point of view of their ability to predict subjective preference ratings of PCM and ADPCM coded speech. The SNR shows an 8-dB bias for PCM coding, i.e., the SNR of the PCM has to exceed the SNR of ADPCM by 8 dB before the two are judged to be equally preferable. In contrast, the segmental SNR shows no such bias. The segmental SNR is considered a better perceptual model since it evaluates the quantization noise with respect to the energy in each underlying speech segment.