Low data rate speech encoding employing syllable pitch patterns

Abstract

The present invention is a speech encoding technique useful in low data rate speech. Spoken input is analyzed to determine its basic phonological linguistic units and syllables. The pitch track for each syllable is compared with each of a predetermined set of pitch patterns. A pitch pattern forming the best match to the actual pitch track is selected for each syllable. Phonological linguistic unit indicia and pitch pattern indicia are transmitted to a speech synthesis apparatus. This synthesis apparatus matches the pitch pattern indicia to syllable groupings of the phonological linguistic unit indicia. During speech synthesis, sounds are produced corresponding to the phonological linguistic unit indicia with their primary pitch controlled by the pitch pattern indicia of the corresponding syllable. This achieves some measure of approximation to the primary pitch of the original spoken input at a low data rate. In the preferred embodiment, each pitch pattern includes an initial pitch slope, which may be zero indicating no change in pitch, a final pitch slope and a turning point between these two slopes.