Abstract:

Brief noise bursts (340-ms, 20-ms rise/fall times) consisting of third-octave bands of noise (center frequencies 0.5, 1, 2, and 4 kHz) and bandpass noises with different degrees of low-frequency content (0.5--4, 1--4, and 2--4 kHz) were recorded binaurally from 17 different locations (90 deg on the left to 90 deg on the right in 11.25-deg steps) at the ears of KEMAR in an anechoic room and a reverberant room. The recorded sounds were processed by attenuating or removing interaural intensity differences (IIDs) and presented to five normally hearing subjects through insert transducers (ER-3A) in a sound-source identification task. The effect on localization accuracy of reducing IIDs by half was not significant. However, reducing IIDs to zero resulted in degraded localization accuracy for noise bands that contained energy above 1000 Hz. The results were similar for signals recorded in a reverberant room as for those recorded in an anechoic room. Results will be discussed with respect to the relative contributions of interaural time differences (ITDs) and IIDs for horizontal auditory localization. [Work supported in part by NIH, NIDRR.]