International Business Machines Corporation

Thierry Liethoudt

Claude R Galand

Michele Rosso

Emmanuel Lancon

Hubert Crepy

Philippe Elie

A pitch detector to adjust long term prediction in a pulse excitation speech coder. A residual signal r(n) is first derived from the speech signal s(n) by short term filtering. Then, r(n) is processed to calculate a prediction error signal e(n) which is subsequently pulse excitation encoded. The processing of e(n) entails prediction of a residual by measuring a pitch related factor M, employing two steps. First calculating a coarse M value through peak clipping and sign transition detection, and then adjusting the M value by autocorrelation--calculations about the roughly spaced peaks.

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Nice, France

Thierry Liethoudt