Lateralization of high-frequency transposed stimuli under conditions of binaural interference

Abstract

The purpose of this study was to determine whether binaural interference would occur if ITD-based extents of laterality were measured using high-frequency transposed stimuli as targets. The results of an earlier study [L. R. Bernstein and C. Trahiotis, J. Acoust. Soc. Am. 116, 3062–3069 (2004)], which focused on threshold-ITDs rather than extents of laterality, suggested that high-frequency transposed stimuli might be immune to binaural interference effects resulting from the addition of a spectrally-remote, low-frequency interferer. In contrast to the earlier findings, the data from this study indicate that high-frequency transposed targets can, indeed, be susceptible to binaural interference. High-frequency transposed targets, even when presented along with an interferer, yielded greater extents of ITD-based laterality than did Gaussian noise targets presented in isolation. That is, the enhanced potency of ITDs conveyed by transposed stimuli persisted even in the presence of a low-frequency interferer. Predictions made using an extension of the model of Heller and Trahiotis [L. M. Heller and C. Trahiotis, J. Acoust. Soc. Am. 99, 3632–3637 (1996)] accounted well for binaural interference obtained with conventional Gaussian noise targets but generally over-predicted the amounts of interference found with the transposed targets.