Separation and integration of sound sources in auditory processing

Abstract

Some perceptual experiments were conducted to elucidate sound source separation processing in speech perception. The phenomenon of phonemic restoration was tested if it occurs in dichotic listening. An original speech is Japanese /VCV/, the stimulus is made by manipulating the /VCV/ as was replaced the consonant part with noise. The duration of replacement was varied at six levels: 10, 20, 40, 60, 80, and 100 ms. There were two hearing modes: in one case, the monaural stimulus was presented to both the ear, and in the other case, the speech part of the stimulus was presented to an ear and the noise part to the opposite ear simultaneously. Thirty subjects in the age of twenties participate the listening test. The results show that phonemic restoration effect is clearly observed in both hearing modes. The rate of restoration is 92%, and 95% even in dichotic listening. There was no feature of speech in the noise has no relation with speech sound. Moreover, the direction of the noise sound was opposite to that of speech sound source, different in 180 degree. Even though the two sound signal are somehow integrated to hear restored speech.