抄録
Audiological tests were performed for sixteen patients with brain stem disorders in order to study their impairment of auditory perception. Their brainstem disorders were caused by tumor, hemorrhage, encephalitis and degenerative diseases, and all of their auditory brainstem responses were abnormal. ABR abnormality was defined by absent ABR or disappearance of later waves or prolongation of wave V-I peak interval.
The following audiological tests were performed:
1) Pure tone audiometry, 2) Speech audiometry, 3) Discrimination test of meaningless 53 monosyllables, 4) Minimal-pair identification test 5) Long vs short vowels identification test, 6) Accent identification test, 7) Prosody identification test and 8) Token test.
The results were as follows:
1) Pure tone thresholds were within normal range in 12 of 16 patients. The remaining four patients showed a mild hearing loss. 2) Speech audiometry showed normal scores in all patients except for two cases with absent ABR. 3) However, the discrimination test revealed lower correct percent in most patients except for cases with prolongation of wave V-I in less than 3 standard deviations. 4) Other tests demonstrated no abnormalities in most patients except for two cases with absent ABR as well as the token test.
Our results indicated that only discrimination test of meaningless 53 monosyllables could detect audiological abnormalities in patients with lesions of auditory pathway in brainstem. And this suggested that the patients were hard to perceive meaningless monosyllables with low redundancy but could hear very accurately other test stimuli with high redundancy.
