Abstract
We reported a case impaired across a range of auditory input processing and spoken word production tasks.
The patient is a 90-year-old right-handed male suffering from a cerebral infarction. MRI revealed a small lesion lying scattered in the left superior temporal gyrus and lower parietal lobe.
His speech was grammatically well formed, but often interrupted by pauses because of selfcorrected phonemic errors. Prolonged, extraordinary pitch and distortion were exhibited. On confrontation naming, he could retrieve lexical representation ; however, similar sound errors were revealed. Surprisingly, in repetition he occasionally replied semantic paraphasias or formal paraphasias. Also, performance showed reverse word frequency and was affected by word imageability. He was entirely unable to repeat nonwords. Reading comprehension was spared. Reading aloud of kana words and nonwords was well preserved. These features share a number of similarities with deep dysphasia.
His auditory word comprehension was nearly preserved. However, in auditory lexical decision tasks he tended to reject all stimuli that he could not recognize with certainty. Auditory phoneme discrimination of TLPA was in the nearly normal range. These features resemble “word form deafness.”
Upon examining the patient's phonological awareness, we found rhyme judgment, homophone judgment and syllable deletion were all poor. He was unable to make associations with phonological representations accurately based on elementary speech sounds. We nevertheless concluded that he recognized a word because he captured the contour or supra-segmental features of words.
The features of both his input and output suggest that the underlying mechanism of his impairments is inability of segmentation of sound structure.
