Interpolation Of The Pitch-Predictor Parameters In Analysis-By-Synthesis Speech Coders

W. Bastiaan Kleijn, Ravi P. Ramachandran, Peter Kroon

Research output: Contribution to journalLetterpeer-review

30 Scopus citations


The pitch-predictor contributes greatly to the efficiency of current analysis-by-synthesis speech coders by mapping the past reconstructed signal into the present. However, for good performance, it is required that its parameters are updated often (once every 2.5-7.5 ms). A slower update rate of the pitch-predictor delay results in time misalignment between the original signal and the pitch-predictor contribution to the reconstructed signal. We introduce a new procedure, that allows a slow update rate of the pitch-predictor parameters without this problem. In this method the original signal is modified in a closed-loop fashion such that the parameter values obtained by interpolation of open-loop estimates form the optimal encoding of the modified signal. This new paradigm is a generalization of the familiar analysis-by-synthesis principle. The generalized analysis-by-synthesis principle can be used for interpolation of both the pitch-predictor delay and gain. We compare, by means of a subjective test, speech signals encoded with different versions of the code-excited linear predictor (CELP) coder. The comparison shows that a pitch predictor exploiting our interpolation strategy, with an update rate of 50 Hz, provides a subjective speech quality similar to a conventional pitch predictor where the parameters are updated for every pitch cycle.

Original languageEnglish (US)
Pages (from-to)42-54
Number of pages13
JournalIEEE Transactions on Speech and Audio Processing
Issue number1
StatePublished - Jan 1994
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Software
  • Acoustics and Ultrasonics
  • Computer Vision and Pattern Recognition
  • Electrical and Electronic Engineering


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