2002 Volume 22 Issue 4 Pages 316-326
The present study quantitatively examined the accuracy of phonemic identification in aphasic patients. Eight aphasic patients with left-hemisphere lesion and 15 normal subjects participated in the study. The speech sounds chosen for the investigation were monosyllables varying by manner of articulation (stops vs. glides). The /ba/-/wa/ continuum consisted of 10 synthesized stimuli varied by transition duration of the first and second formants (F1 and F2) . The accuracy of /ba/-/wa/ identification was assessed in terms of formant transition duration in the subjects' right ear.
The following results were obtained. (1)The accuracy of /ba/-/wa/ identification in the right ear of aphasic patients was significantly poorer than that of normal subjects ; that is, phonemic identification performance was deteriorated in many aphasic patients. (2)The /ba/-/wa/ identification performance (normal/borderline/abnormal) moderately correlated with auditory resolution performance in the right ear of the aphasic patients as measured using the click fusion threshold test (normal/borderline/abnormal). However, the correlation between /ba/-/wa/ identification accuracy and the click fusion threshold was below a significant level.
We concluded that (1)the degraded identification function in the right ear of aphasic patients may be partly attributable to disturbance of auditory resolution, and (2)also partly attributable to inability to assign reliable category labels to speech stimuli based the memory of phonemes.