Hubert Crepy

Method and apparatus for expanding the vocabulary of a speech system

A computerized method is provided for adding a new word to a vocabulary of a speech system, the vocabulary comprising words and corresponding acoustic patterns for a language or language domain. Within a determination step for the new word, a regularity value is determined which measures the conformity with respect to the pronunciation in the language or language domain. In a comparison step, the regularity value is compared to a threshold value to decide whether the conformity is insufficient. Only in the affirmative case of insufficient conformity, a prompting step is performed, prompting for additional information on the pronunciation of the new word. Finally, in an extension step, the new word and an acoustic pattern of the new word are added to the vocabulary.

Pitch detection for use in a predictive speech coder

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.