Techniques for improving subjective quality of PSI-CELP and its evaluation results

Kazunori Mano, Kumiko Oguchi, Kazunaga Ikeda

Research output: Contribution to journalArticlepeer-review


This paper describes techniques for evaluating and improving subjective quality of PSI-CELP speech coding. In low bit-rate speech coding, it is impossible to design good coders based on only objective evaluation measures such as SNR, SNRseg, and cepstral distances: subjective evaluation is essential. The PSI-CELP codec for mobile communications has been designed to be optimal under the following conditions: error free, burst error, low level power, and background noise. A perceptual weighting filter and a postfilter improve the subjective quality. The relationships between subjective and objective evaluation measures have been investigated to obtain error-robust coders. The subjective quality of the resulting half-rate PSI-CELP codec is better than that of the Japanese full-rate codec.

Original languageEnglish
Pages (from-to)405-412
Number of pages8
JournalNTT R and D
Issue number4
Publication statusPublished - 1994 Jan 1
Externally publishedYes

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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