A technique for investigating on-off patterns of speech

A study is made of certain properties of speech which are concerned with determining the presence of speech on a telephone circuit. A speech detector is constructed to yield an output of spurts and gaps, corresponding to the presence or absence of energy above a threshold. A computer program then attempts to correct this pattern for spurious noise operation and for gaps due to stop consonants, eventually yielding a pattern of talkspurts and pauses. Data reported here include the distributions of the spurts and gaps resulting from the detector as well as the distributions of talkspurts and pauses from the computer program. Studied here are the influence on these distributions of detector threshold variations as well as of parameter variations within the computer program. The gaps occurring within talkspurts retain their distribution over a range of thresholds, but the spurts do not. It appears that 200 msec forms a boundary between intersyllabic gaps and listener-detected pauses. The detection technique developed here is considered to be an improvement over conventional methods, but still yields data whose significance is uncertain. It may be that a simple automatic speech detecting technique using fixed parameters is inadequate for some purposes.