A comparison of speech envelopes of stutters and nonstutterers.

A new parameter, the area under the speech envelop, was used to evaluate the degree of speech dysfluency in stutterers. This parameter has been measured for 100-s utterances of 30 fluent speakers and 30 stutterers speaking with simultaneous auditory feedback (SAF) and delayed auditory feedback (DAF). A correlation was found between the area under the speech envelope and the severity of stuttering. Thus for stutterers, this parameter can be used to evaluate the degree of the disturbance of fluency. The values of this parameter were significantly higher in fluent utterances than in nonfluent ones. The reduction of stuttering observed in stutterers under DAF was accompanied by an increase of the area under the speech envelope, making it comparable to the one measured for the utterances of fluent speakers.