Irwin Pollack
Mental Health Res. Inst., Univ. of Michigan, Ann Arbor, MI 48109-0720
Pairs of repeated noise patterns were presented to each ear: one pair with the same fundamental repetition frequency, and one pair with a slightly different fundamental frequency. The task of the listener was to identify the ear with frequency asynchrony. Under conditions where the detection of frequency asynchrony of complex sounds is nearly perfect, the discrimination of which ear exhibits the asynchrony is near chance. Several lines of evidence suggest that the latter difficulty is related to binaural processing of frequency asynchrony across the two ears. Evidence: (1) the accuracy of detection of binaural frequency asynchrony rivals that of monaural frequency asynchrony; (2) the introduction of interaural intensity differences between the two ears improves which-ear discrimination, and reduces binaural asynchrony discrimination; (3) under conditions of equivalent monaural asynchrony, which-ear discrimination reflects differences in binaural asynchrony.