Some Acoustic Aspects of Stuttered Speech

Abstract

Three extensive studies have been conducted on the acoustic features of stuttered speech. One study examined the temporal properties and formants of speech having various degrees of fluency. Another study reports on the coarticulation patterns across two languages (Italian-English) of stutterers and nonstutterers. The third study (discussed more extensively) is on the spectrographic patterns of simultaneous intraoral air pressure and formant patterns of stutterers and nonstutterers. Stutterers and normal speakers produced a series of syllables of /pa, ba, ap, ab, apa, aba/ and some short phrases. Simultaneous measures of intraoral air pressure and formant patterns of these utterances reflected the transitional features of labial release to glottal onset patterns, e.g., plosive to vowel. Also, vowel and plosive measurements reflected the manner of glottal termination followed by labial closure. Standard spectrographic tracings illustrate only the acoustic events of speech and pose certain problems of accurate temporal measurements for stutterers, since a great deal of their speech efforts are essentially nonacoustical. A system is presented that yields a more discrete pattern of the articulatory events in terms of formant patterns and intraoral air pressure. The transitional features in the fluent and nonfluent production of syllables uttered by stutterers and nonstutterers will be illustrated. The difference is shown to be within the transitional aspects of segmental units. The transitional features within the syllabic structure of the stuttered speech point to a disruption of coarticulated events. This transitional failure is the phenomenal core of stuttering. Implications will be discussed, particularly that voice control is the core element in stuttering behavior.