A survey of speech bandwidth compression techniques

Application of speech bandwidth compression techniques to voice communications provides the promise of more efficient utilization of the available radio spectrum and the possibility of improved performance of noisy, long distance communications links. That significant potential gain exists is evident from the fact that the information rate required for transmission of the conventional speech signal is approximately 24,000 bits per second, whereas that for transmission of the equivalent word-intelligence content by means of teletype is 75 bits per second. The paper presents brief descriptions of several speech bandwidth compression techniques which are currently being employed or investigated to achieve varying degrees of compression. Also a method of estimating the influence of signal-to-noise ratio on a communications link employing such compression techniques is presented.