Empirical and theoretical findings concerning how interaural intensitive disparities affect lateralization for high- versus low -frequency stimuli.

Abstract

This presentation concerns empirical and theoretical findings concerning the potency of interaural intensitive disparities (IIDs) at low versus high spectral frequencies. In one context, an acoustic pointing task was used to measure how IIDs affect extents of laterality. Laterality was measured for 4-kHz-centered stimuli with reinforcing or opposing combinations of IIDs and interaural temporal disparities (ITDs). The goal was to assess whether IIDs act as scalars or “weights” within the putative “binaural display” at high spectral frequencies (where the envelopes convey ITD-information) as they have been repeatedly shown to operate at low spectral frequencies (where the waveforms convey ITD-information). They do. The data were accounted for via an augmentation of the cross-correlation-based “position-variable” modeling approach developed by Stern and Shear [J. Acoust. Soc. Am. 100, 2278–2288 (1996)] to account for ITD-based lateralization at low spectral frequencies. In a second context, laterality produced by IIDs (ITD=0) was measured for stimuli centered at either 4 kHz or 500 Hz. The novel finding was that IIDs consistently produced larger extents of laterality at 4 kHz than they did at 500 Hz. [Work supported by research Grant No. NIH DC-04147 from the National Institute on Deafness and Other Communication Disorders, National Institutes of Health.]