Pronunciation errors in acquired speech disorders: the errors of our ways.

There are conflicting arguments over whether perceptual analysis of speech errors can be used for a differential diagnosis of acquired motor speech disorders. This study addressed the issue using a narrow phonetic transcription of single-word naming and repetition responses, and a comprehensive taxonomy of error types. Speaker groups were selected according to criteria which were not variables to be investigated later. The listener-perceived segmental errors of 30 post-stroke speech-impaired speakers (six spastic dysarthric; 12 speech dyspraxic and phonemic paraphasic without dysphasia; 12 speech dyspraxic and phonemic paraphasic with dysphasia) were analysed and subjected to statistical analysis. A variety of analyses failed to establish any consistently reliable differential diagnostic pointers. It is concluded that reasons for the inconclusiveness of perceptual assessment go beyond investigatory methodological problems and embrace issues of underlying theory as well.