An analysis of the intonational structure of stuttered speech

While previous studies have successfully revealed areas vulnerable to disfluency at the word level in stuttering, identifying the specific factors responsible for this instability has proved difficult. Analyzing the effects of phrasal prosody, which governs such word-level factors as lexical stress [1], is critical in order to account for the relations between wordlevel and phrase-level effects, and how they affect patterns of disfluency in stuttered speech. In a story-telling task performed by two stutterers and two control subjects, it was found that stutterers' disfluencies were accompanied by more prosodic irregularities prior to the actual cause of the disfluency. In particular, changes in f0 and duration affect the realization of cues in the disfluent environment, resulting in fundamental alterations of intonational phrase structure. Anticipatory and target-realized disfluencies contribute different acoustic cues to their immediate environments, the results of which often create conflicting prominence relationships among prosodic constituents, thereby losing information key for conveying meaning.