Phonetic disintegration in aphasia: acoustic analysis of spectral characteristics for place of articulation.

In this study, we attempted to determine whether phonetic disintegration of speech in Broca's aphasia affects the spectral characteristics of speech sounds as has been shown for the temporal characteristics of speech. To this end, we investigated the production of place of articulation in Broca's aphasics. Acoustic analysis of the spectral characteristics for stop consonants were conducted. Results indicated that the static aspects of speech production were preserved, as Broca's aphasics seemed to be able to reach the articulatory configuration for the appropriate place of articulation. However, the dynamic aspects of speech production seemed to be impaired, as their productions reflected problems with the source characteristics of speech sounds and with the integration of articulatory movements in the vocal tract. Listener perceptions of the aphasics' productions were compared with acoustic analyses for these same productions. The two measures were related; that is, the spectral characteristics of the utterances provided salient cues for place of articulation perception. An analysis of the occurrences of errors along the dimensions of voicing and place showed that aphasics rarely produce utterances containing both voice and place substitutions.