Stress, rate, and phone duration in apraxia of speech

Author

Linda Byrum Lilley

Date of Award

12-1982

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Speech and Hearing Science

Major Professor

Patrick J. Carney, Ellen I. Hamby

Committee Members

Harold L. Luper, Stephen J. Handel

Abstract

The purpose of this study was to assess, for subjects with apraxia of speech and for normal speakers, phone durations and trends of phone duration when syllabic stress, speaking rate, and meaning were varied. Subjects were ten apraxic and five normal speakers. The subjects produced a word (permit) and a nonsense syllable (perpit), both with two different syllabic stress patterns. Utterances were produced in the carrier phrase, "My _ please" and were spoken at normal and at fast rates. Durational measurements were obtained from oscillographic displays for the following segments: both vowels and the medial consonant in the target word, the target word, and the entire phrase. Only utterances which were perceptually correct in terms of articulation and stress were analyzed.

The apraxic speakers had longer phrase, word, and phone durations than normal speakers. However, apraxics maintained the same relative phone/word durations as the normals. Therefore, apraxia does not appear to be a disorder of the durational relations among phones.

In talking at the faster rate, normal subjects proportionately decreased phone, word, and phrase durations. There was considerable durational overlap between apraxics' productions at the two rates. While it is unclear as to why apraxics did not change speaking rate, altering rate was aberrant in the apraxic speakers. Thus, the mechanism for changing speaking rate may be involved in apraxia.

Most durational findings applied to apraxic and normal speakers for meaningful and nonsense stimuli, although there was greater durational variability for both speaking groups for the nonsense syllables. Other than the increase in durational variability, there do not seem to be temporal differences between the production of meaningful and nonsense stimuli.

Insofar as perceptually correct utterances are representative of apraxics' speech, it can be inferred that apraxia is not a disorder of the durational relations among phones. It was hypothesized that apraxia is a disorder in the selection of the correct program for the target utterance. Implications for a theory of apraxia were discussed.

Recommended Citation

Lilley, Linda Byrum, "Stress, rate, and phone duration in apraxia of speech. " PhD diss., University of Tennessee, 1982.
https://trace.tennessee.edu/utk_graddiss/13274