Spectrographic analysis of vowel and word duration in apraxia of speech

Most normal speakers of English reduce the duration of the stem word vowel as words increase in length. Theoretically, this durational reduction reflects low-level linguistic knowledge. We posed two questions in this study: First, do speakers with apraxia of speech progressively reduce vowel durations as words increase in length, and second, do these vowel and word durations differ significantly from normal productions? We asked 11 apraxia of speech patients and 11 normal speakers to repeat three sets of three words which progressively increased in length, and we analyzed these productions spectrographically. Our results revealed that both groups reduced vowel duration as words increased in length. Word and vowel duration for apraxia of speech patients, however, were often significantly longer than those for normal speakers. Our results suggest that vowel reduction is a robust phenomenon which resists impairment in apraxia of speech, despite often significant disturbances in motor programming.