Lateralization of a perturbed harmonic: effects of onset asynchrony and mistuning.

The lateralization paradigm of Trahiotis and Stern [C. Trahiotis and R. M. Sern, J. Acoust. Soc. Am. 86, 1285-1293 (1989)] was extended to investigate the influence of a spectrally flanking complex on the lateral position of a perturbed harmonic. When a complex tone consisting of harmonics 2 through 8 or 100 Hz was presented with an interaural time difference (ITD) of 1.5 ms, the complex was heard on the leading side (experiment 1). However, when the 500-Hz component had a later onset time than the other components (experiments 1 and 2) or was mistuned (experiment 3), it was perceived to be in a different lateral position to the complex. The complex still maintained a residual influence on the lateralization of the pure tone even for the largest asynchrony used (experiment 4). Experiment 5 confirmed that the lateralizaiton of the tonal complex was consistent with the aggregation of binaural information across frequency. The results suggest that across-frequency integration of interaural-timing information is influenced by onset-asynchrony and harmonicity.