Speech Timing in Apraxia of Speech Versus Conduction Aphasia

TLDR

Apraxia of speech and conduction aphasia involve motoric and phonological deficits that affect speech timing. The study examined temporal speech parameters in individuals with apraxia of speech, conduction aphasia, and normal speech. Participants repeated target words in a carrier phrase ten times while acoustic measures of stop gap, voice onset time, vowel nucleus, and CV duration were recorded. Speakers with apraxia of speech showed longer, more variable stop gaps, vowels, and CV durations, and greater token‑to‑token variability that correlated with perceptual judgments, whereas those with conduction aphasia had longer vowel and CV durations compared to normal speakers.

Abstract

This study examined temporal parameters of speech in subjects with apraxia of speech, conduction aphasia, and normal speech. They were asked to repeat target words in a carrier phrase 10 times. Acoustic analyses involved measurement of stop gap duration, voice onset time, vowel nucleus duration, and consonant-vowel (CV) duration. Speakers with apraxia of speech had longer and more variable stop gap, vowel, and CV durations than did subjects with aphasia or normal speech. Speakers with conduction aphasia had longer vowel durations and CV durations than subjects with normal speech. Also, subjects with apraxia of speech showed greater token-to-token variability than the other subject groups. The variability shown by subjects with apraxia of speech was significantly correlated with perceptual judgments of their speech. The significance of these results is discussed in the context of motoric and phonological explanations for apraxia of speech and conduction aphasia.