The effect of temporal manipulation on the perception of disfluencies as normal or stuttering

The purpose of this investigation was to study the effect of temporal features within repetition of speech segments on the perception of stuttering. Past research has provided evidence that certain temporal aspects of repetitions produced by people who stutter tend to be shorter than those produced by normally fluent speakers. The effect of these temporal factors on the perception of the disfluency as "stuttering" or "normal" has not yet been studied. Conversational speech of five children who stutter was recorded. Two short utterances. one containing part-word repetition (PWR) and one containing whole-word repetition (WWR), were identified in the speech of each child and then manipulated by the CSL and CSpeech computer softwares. Two selected elements within repetitions, namely the vowel of the repeated unit and the interval between the repeated units (e.g., but-but), were lengthened to simulate normal disfluency. Results indicated that both factors (interval duration and vowel duration) moderately affected listeners' perception. In general, repetitions with short vowel and interval durations were judged as more representative of stuttering, whereas repetitions with longer vowel and interval duration were judged as more representative of normal speech.

As a result of this activity, the reader will learn about (1) various factors that influence the perception of disfluent segments as stuttering, (2) the special effect of duration of specific elements within repetitions on the perception of disfluency as stuttering, and (3) the possible implications of the new information for therapeutic considerations.