Distortion Measures for Speech Coding
Aloknath De · IETE Technical Review · 1998
In this article, we have reviewed some of the existing subjective and objective measures used in the area of speech coding. The mean opinion score and the diagnostic acceptability measure are two of the widely used subjective measures. The most popular class of the time-domain measures is the signal-to-noise ratio (SNR) with its variants such as the segmental SNR, the granular segmentsal SNR etc. Among the spectral distortion measures, the log likelihood ratio measure, the log area ratio measure, the log spectral distortion measure, the cepstral distance and the Itakura-Saito distortion measure are quite well-known. Some of the more recently proposed objective measures place emphasis on the perceptually significant aspects. Three such classes of the psychoacoustically-motivated measures are the information index, the Bark spectral distortion measure and the neural distance measure (e.g., the cochlear discrimination information, the cochlear hidden Markovian measues). The merit of considering important perceptual events is evident in the success of these measures.