Phonetic and/or phonological disorders in aphasic speech: An acoustic study of speech output in 4 Broca’s and 4 conduction aphasics

According to speech production models such as Levelt’s (1989), speech errors in aphasia can arise at different levels of processing: lexical, phonological or phonetic. It has been claimed that each type of aphasia is associated with a specific speech production disorder. Conduction aphasia is characterized predominantly by a breakdown of the phonological code, whereas Broca’s aphasia is a disorder affecting mostly the phonetic level. However, Blumstein (1973) argued against a typology of errors as a basis for the discrimination of different clinical pictures of aphasia and postulated that the type of errors should remain similar across all the aphasic groups. Such inconsistencies in the findings and in their interpretations are the result of different methodologies and research tools.