PITCH EXTRACTION FOR SPEECH SYNTHESIS WITH SPECIAL TECHNIQUES FOR USE IN DIGITIZED BANDWIDTH COMPRESSION SYSTEMS

摘要

Pitch channel techniques for voice compression systems are reviewed. Time and frequency domain methods for pitch extraction are compared. The problem of extracting pitch from band-limited circuits which have no fundamental present is treated. Techniques are shown for improving the rise and fall resolution of the inverted pitch analog signal. Digital transmission of pitch channel information at rates below 150 bits per second is discussed. A hiss-buzz segmenter is described: for use in pitch channel squelch, selecting hiss or buzz excitation, reducing rise time of derived pitch analog signal, and a special bit-rate reduction technique in digital signal transmission. Tracking requirements for a universal pitch extractor are discussed. Pitch roughness, pitch AGC, and a linear buzz oscillator are also treated. The pitch channel used in the AFCRC Scanyocoder is described in detail.