ARTICULATORY CONSISTENCY AND VARIABILITY IN APRAXIA OF SPEECH

ANTHONY GEORGE MLCOCH, Purdue University

Abstract

The statement that apraxia of speech is characterized by a high degree of articulatory inconsistency and variability has been primarily based on clinical observation and not on systematic and quantitative research. The purpose of the present study was to investigate systematically and quantitatively the articulatory consistency (i.e., tendency to misarticulate the same words across repeated trials) and variability (i.e., tendency to produce different errors in the same words and word positions across repeated trials) exhibited by individuals with apraxia of speech within different forms of contextual speech. Six subjects with relatively pure apraxia of speech were asked to recite the "Pledge of Allegiance" (automatic speech task), orally read a 76-word passage (oral reading task), and describe a series of pictures (self-formulated speech task), three times under three experimental conditions. These conditions were a no stress condition in which the subject performed each task at his own pace, a situational stress condition in which each task was performed in front of an audience, and a communicative stress condition in which the subject was asked to perform each task at a supernormal rate of speech. The subjects' responses were tape recorded and later phonetically transcribed. Criterion measures of consistency and variability as well as frequency of error were obtained. The following results were obtained: (1) the type of stress condition or contextual speech task had no significant effect on the articulatory frequency, consistency, and variability exhibited by the subjects; (2) a consistency and variability effect was found in each type of contextual speech task; (3) the length or the phonetic difficulty of a word was not found to have a significant effect on the frequency or consistency of apractic articulatory errors; (4) more articulatory variability was associated with polysyllabic words produced within the situational and communicative stress conditions; and (5) the severity of the apractic speech disturbance was significantly related to articulatory frequency and consistency.

Degree

Ph.D.

Subject Area

Speech therapy

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