B.S.T.J. Briefs: Interpolation of Data With Continuous Speech Signals

BRIEF Interpolation of Data With Continuous Speech Signals By M. R. SCHROEDER and S. L. HANAUER (Manuscript received March 1, 1967) In some communications systems, the need arises for temporally interpolating data or signalling information during continuous speech.1 If the required time gaps are created by simply interrupting the speech signal, severe degradation of speech quality and some loss in intelligibility results. The reason for the degradation is twofold: (i) The interruptions introduce discontinuities in the speech signal-- two for eveiy interruption. (u) The interruptions, unless occurring pitch synchronously, create an inharmonic signal. In the following, a proposal is described which avoids discontinuities and is pitch synchronous--without the need for pitch detection. Average "off-time" ratios of 30 percent have been achieved for continuous speech without audible degradation. These results were obtained by computer simulation of a sampled data system. The instrumentation for a realtime analog system is simple. The gaps created by this method occur at irregular intervals in time. Thus, for a steady flow of data or signalling information, some buffer storage and coding that distinguishes "gaps" (interpolated data) from speech is required. In the proposed interpolation system, the speech signal s(t) is divided by its envelope a(t) = [st) + *»(#]* 2 (1)