The cochlear delay shifts the arrival of lower-frequency components of an auditory signal slightly but systematically behind that of higher-frequency components. Therefore, even if all of the components of a complex tone physically begin simultaneously, their temporal relation is not preserved at the cochlear level. In our previous study, the accuracy of synchrony judgment was measured using two types of chirps (compensated and enhanced chirps) and a pulse. The compensated chirp had an increasing frequency pattern to cancel out the cochlear delay. An enhanced chirp had a delay pattern that enhances the assumed cochlear delay. The pulse had a usual cochlear delay at the auditory peripheral. As a result, the accuracy of synchrony judgment was the highest in the pulse and higher in the enhanced chirp than the compensated chirp, implying that there is an asymmetric aspect. The purpose of this study is to investigate how our auditory system processes this asymmetric aspect, and to investigate the extent of the amount of temporal collapse was tolerated. We also measured the accuracy of synchrony judgment using stimuli that reverse the cochlear delay (the higher-frequency components arrive behind the lower-frequency components), or enhance the delay of lower-frequency components up to 8 times.

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