Single word intelligibility in aphasia and apraxia of speech: A phonetic error analysis

This study examined the phonetic differences between word productions attem pted by aphasic speakers and listeners' perceptions of these productions. T en speakers with aphasia and apraxia of speech, ten with aphasia only and t en normal speakers produced 70 monosyllabic words. Listeners orthographical ly transcribed the words they thought the speakers were saying. The target and transcribed words were compared and phonetic differences noted. There w as no significant difference in the frequency of target-transcription discr epancies between vowels and consonants or between consonants in prevocalic and postvocalic position for any of the speaker groups. In addition to a gr eater number of errors, the phonetic error profiles of aphasic speakers wit h and without apraxia of speech were different from that of normal speakers . Among apraxic speakers, different error patterns were found in speakers w ith high overall intelligibility than in speakers with low to moderate over all intelligibility. The frequency of errors affecting place of articulatio n for stops and nasals was highly correlated with overall speech intelligib ility. Other common phonetic confusions for the apraxic speakers included c onfusions between singleton and consonant clusters, and between presence an d absence of word initial /h/. There was substantial individual variability across apraxic speakers for several other phonetic contrasts.