Some factors affecting intelligibility in single sideband communications

Of all the factors that make up the design of a single sideband (SSB) speech transmission system, the one on which information is most difficult to obtain is that of intelligibility as affected by errors of carrier frequency. The problem is more difficult because of the subjective nature of the judgements that influence users to accept or condemn a given compromise. Of all the military and engineering personnel who are expected to express an opinion on this subject, only a small percentage have had the opportunity to hear the effects discussed under controlled and measured conditions. The purpose of this paper is to describe certain tests of this type and explain one interpretation of the indicated course of action.