600-Bit-Per-Second Voice Digitizer (Linear Predictive Formant Vocoder).

摘要

Past efforts to achieve practical formant vocoders have been plagued with problems of formant tracker instability, resulting in unnatural warbles in the synthesized speech. A new approach to formant frequency determination, combined with a digital implementation, promises to eliminate these effects and to yield a useful formant vocoder. Additional redundancy reduction of information is obtained by means of a pattern-matching technique, which encodes the three formant frequencies into seven bits per frame to provide speech synthesis at 600 bps. This is accomplished by using an existing 2400-bps linear-predictive-encoder (LPE) with some additional processing. A demonstration record of processed speech at 600 bps is included with the report. (Author)