1979 年 35 巻 10 号 p. 537-543
Possible location of a context-dependent perceptual mechanism in the human auditory system is investigated through experiments on dichotic fusion. As an experimental hypothesis, peripheral/central dichotomy of the perceptual mechanism has been assumed by taking a model of dichotic fusion into account. Two types of dynamic vowels, one the form[u-Vowel-u]and the other the form[e-Vowel-e], were synthesized to form a pair of the dichotic stimuli. A stimulus of one type was presented to one ear and the counterpart of the other type to the opposite ear simultaneously. Two experimental conditions, condition #1 and #2, were set up for the pairs of stimuli. In condition #1, formant frequencies of the middle vowels in each pair of stimuli were the same or very close to each other but differed in phonetic quality, while in condition #2, formant frequencies of them were different but the same in phonetic quality. Listeners were asked to make judgment of fusion for the middle vowels of each dichotic pair. It has been found that the fusion occurs for stimuli in it condition #1 but does not in #2, that is, when the formant frequencies of the two vowels are very close irrespective of their phonetic quality. This suggests that the context-dependent mechanism dose not take place in the peripheral auditory system but is likely to be a function of the central processes.