Perceptual and acoustic analyses of speech sound errors in apraxia of speech accompanied by aphasia

Abstract

In order to carefully characterise their speech errors, two individuals with apraxia of speech and aphasia were audiotape recorded producing 650 monosyllabic words in imitation. Each utterance was transcribed using the methods and diacritics for close phonetic transcription described by Shriberg and Kent (1995). In addition, utterances were analysed acoustically. Although the subjects demonstrated some differences, they also displayed similar patterns. Both produced perceived substitutions as well as perceived distortions. While errors on initial stops tended to be classified as substitutions, errors on initial fricatives were more often classified as distortions or distorted substitutions. Acoustic analyses confirmed and augmented perceptual judgements. The results indicated that this type of approach can be useful for furthering our understanding of the nature and underlying cause of the speech disorder in individuals with aphasia and apraxia. The implications of these findings for the distinction between phonetic and phonemic errors are discussed.