The dependence of binaural detection and interaural discrimination on interaural time and intensity in normal and impaired listeners

Abstract

Measurements of binaural performance by normal and hearing‐impaired listeners are reported for large reference values of interaural time delay (ITD) and interaural intensity difference (IID). NoSπ detection thresholds and just‐noticeable differences (jnds) in ITD and IID were measured with 1/3‐oct noise bursts at 500 and 4000 Hz, using reference ITDs and IIDs up to 600 μs and 34 dB. As expected, jnds and thresholds for normal and impaired subjects increase as the reference IID increases. In contrast, increasing the reference ITD shows relatively small effects for most subjects. The present data are consistent with those described previously [C. Passaro, J. Koehnke, and H. S. Colburn, J. Acoust. Soc. Am. Suppl. 1 79, S21–S22 (1986)] but are more pronounced with larger reference ITDs and IIDs. For example, performance is generally poorer for the impaired listeners than the normal listeners. Also, for both groups, measurements of IID jnds consistently result in smaller jnds for the canceling combinations of reference ITD and IID than reinforcing combinations. [Work supported by NIH.]