Perceptual characteristics of vowel and prosody production in apraxic, aphasic, and dysarthric speakers.

Narrow phonetic transcriptions and prosodic judgments were made of single-word imitations by apraxic (AOS), conduction aphasic (CA), and ataxic dysarthric (AD) speakers. AOS and AD subjects showed similar vowel error patterns, particularly predominant errors in low, tense, and back vowels, more distortions than other types of vowel errors, and predominant errors in initial position of words and in monosyllabic words. The CA subjects displayed a different vowel error pattern, notably more substitutions than distortions, more errors in polysyllabic than monosyllabic words, and more errors in noninitial than initial positions of words. Analysis of prosodic features identifiable at the single-word level (e.g., syllabic stress, juncture, and struggles to initiate or complete productions) indicated that syllabic stress errors and more difficulty initiating than completing word production were characteristic of AOS and AD but not CA subjects.