FEASIBILITY STUDY OF TRANSISTORIZED CODER-MULTIPLEXER
Abstract
The initial engineering phases undertaken to determine the feasibility of providing a system of multiple vocoders fed from telephone inputs and operating over a single voice frequency channel are discussed. An important consideration is the improvement of voice quality over that of conventional speech compression devices. To this end: (a) voice excited and channel vocoders are investigated to determine a means for optimum pitch extraction in the absence of the fundamental pitch frequencies of talkers, compatible with minimum baseband requirements; (b) means for the measurement of speaker recognition are developed; and (c) comparisons of speaker recognition are made between a hybrid vocoding arrangement and several channel vocoders employing 17, 22 and 27 channels. It is shown that pitch may be derived in the absence of the speaker's fundamental voice frequencies. It is also shown that a significant improvement in speech quality can be accomplished when a direct baseband is added to a channel vocoder and voice excitation techniques are applied. Multiplexing means necessary to establish the maximum number of complete speech channels within a telephone frequency range are discussed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1960
- Accession Number
- AD0252335
Entities
People
- Arthur S. Howell
Organizations
- General Dynamics