Effect of source location and listener location on ILD cues in a reverberant room
Antje Ihlefeld, Barbara G. Shinn‐Cunningham · The Journal of the Acoustical Society of America · 2004
Short-term interaural level differences (ILDs) were analyzed for simulations of the signals that would reach a listener in a reverberant room. White noise was convolved with manikin head-related impulse responses measured in a classroom to simulate different locations of the source relative to the manikin and different manikin positions in the room. The ILDs of the signals were computed within each third-octave band over a relatively short time window to investigate how reliably ILD cues encode source laterality. Overall, the mean of the ILD magnitude increases with lateral angle and decreases with distance, as expected. Increasing reverberation decreases the mean ILD magnitude and increases the variance of the short-term ILD, so that the spatial information carried by ILD cues is degraded by reverberation. These results suggest that the mean ILD is not a reliable cue for determining source laterality in a reverberant room. However, by taking into account both the mean and variance, the distribution of high-frequency short-term ILDs provides some spatial information. This analysis suggests that, in order to use ILDs to judge source direction in reverberant space, listeners must accumulate information about how the short-term ILD varies over time. [Work supported by NIDCD and AFOSR.]