AN EVALUATION OF SPEECH COMPRESSION TECHNIQUES
Abstract
The results of previous technical reports are summarized and the results of tests of various recently developed speech compression systems are presented and analyzed. The results can be summarized as follows: (1) Semi- vocoders, operating at 9600 bits/sec, and channel vocoders, at 2400 bits/sec, will provide speech of adequate intelligibility and quality for most military communications. The voice quality of the semi-vocoders will usually be somewhat superior to that of the channel vocoders. (2) Results with as yet in complete systems suggest that the Tarasoff-Daguet technique and the narrow-band spectrum sampling technique will ultimately provide speech intelligibility and quality comparable to that of the semi-vocoder. These systems will also require about 9600 bits/sec channel capacity during transmission. (3) Formant-tracking vocoders operating at about 1200 bits/sec can probably be developed to the point where they will provide speech intelligibility comparable to that from the channel vocoders operating at 2400 bits/sec. At the present time formant- tracking vocoders operating a bits/sec do not provide for adequate speech intelligibility. (4) Transmitting a restricted set of speech 'patterns,' from a larger set obtained from a digitized vocoder-type of speech analyzer- synthesizer, may provide a reduction in the information transmission rate normally required by that particular vocoder. Although this 'pattern' matching technique is still in its early experimental stages it appears that the normal bit rate for a given vocoder system may, by this technique, be reduced to 2/3 and possibly to 1/2 its normal magnitude.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 25, 1963
- Accession Number
- AD0402604
Entities
People
- Jay H. Ball
- Karl D. Kryter
Organizations
- BBN Technologies