ASA 125th Meeting Ottawa 1993 May

2pMU6. Effect of onset asynchrony and mistuning on the lateralization of a pure tone embedded in a harmonic complex.

Nicholas I. Hill

C. J. Darwin

Lab. of Exptl. Psychol., Univ. of Sussex, Brighton BN1 9QG, UK

The effect of onset asynchrony and mistuning on the binaural processing of multi-tone stimuli was investigated using a paradigm derived from that of Trahiotis and Stern [C. Trahiotis and R. M. Stern, J. Acoust. Soc. Am. 86, 1285--1293 (1989)]. A tonal complex comprising harmonics 2 to 8 of 100 Hz and presented with an IDT of 1.5 ms gave rise to a single image lateralized towards the ear receiving the leading signal. However, when the central 500-Hz component was delayed by 40 ms relative to the flanking tones, it was heard out as a separate tone shifted towards the opposite side of the head. Similar effects were observed when the 500-Hz component was mistuned from the flanking complex, with shifts of (plus or minus)3% being sufficient for the mistuned component to be lateralized in the vicinity of the mid-line. The results demonstrate that both onset asynchrony and mistuning influence which frequency components IDT information is integrated across. [Work supported by UK SERC and MRC.]