Onomatopoetic expressions for the test tones presented by pure-tone audiometer were investigated in 27 affected ears of surgically proven unilateral acoustic neuroma (AN) and were compared with them in 37 normal hearing ears. The test tones were pure-tones with the intensity of 10 dB above hearing threshold at 7 frequencies with an octave step between 125 Hz and 8 kHz. The test tones were presented through a headphone and the subjects were asked to describe their subjective expressions of the nature of test tones by using onomatopoeias.
The results obtained were as follows:
1) Although the subjects number of affected ears of AN was less than that of normal hearing ears, more various kinds of onomatopoeia were used as subjective expressions in affected ears of AN than in normal hearing ears at each of 7 frequencies.
2) When the onomatopoeias and the incidence in description at each of 7 frequencies were analysed, the incidence of the most frequently used onomatopoeia in normal hearing ears decreased in affected ears of AN. Also, other onomatopoeias were used in affected ears of AN at each of 7 frequencies, which were never used in normal hearing ears.
3) When the incidence in description of 4 representative onomatopoeias at each tested frequency was analysed, marked differences were found between affected ears of AN and normal hearing ears.
4) It was suggested that marked differences in onomatopoetic expressions against the external test tones between affected ears of AN and normal hearing ears could be caused by the deterioration of frequency selectivity in affected ears of AN which might be due to the intricate pathophysiology induced by the coexistence of cochlear and retrocochlear dysfunctions.
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