日本語破裂子音及び母音の知覚におけるＲｉｇｈｔ Ｅａｒ Ａｄｖａｎｔａｇｅ

Abstract

Dichotic listening tasks, in which competing signals were presented to both ears, were used to study the higher central auditory function and dysfunction. Dichotic speech listening technique revealed the hemispheric lateralization of the brain. The right ear advantage (REA) for speech perception is the index of left-hemispheric language dominance.The study was to elucidate emergence of the dichotic REA for Japanese stop consonants and vowels presented simultaneously to the left and right ears. The competing task I (CV versus CV) and task II (CV, CV versus V, V) were performed for twenty right-handed listeners with normal hearing sensitivity.The results were as follows:1) The identification score of Japanese stop consonants that the ending of CV monosyllables were cut off into 192.0ms in the duration, were 95.3% at the left ear and 95.4% at the right ear.2) In dichotic listening of paired stop consonants, the proportion of REA was significantly larger in short duration group than in long duration group.3) The advantage for the right ear was larger for voiceless stop consonant in simultaneous competing situation.4) The identification of vowels presented to the right ear was 78.0% in dichotic listening of stop consonant versus vowel. In the listening situation, it was showed that Japanese vowel signals travel the path from the right ear to the left hemisphere and could be identificated and recognized.