Spectral weighting of interaural time- and level differences for broadband signals

Abstract

An important ability of the auditory system is to localize sound sources in complex acoustical environments. Two important cues for localization are interaural time- and level differences (ITD, ILD). The sensitivity to these cues differs across frequency and has previously been estimated through frequency-specific detection thresholds. Detection thresholds of ITDs/ILDs are, however, affected by stimulus energy in remote spectral regions, referred to as binaural interference. In this study, the spectral weights of ITD- and ILD cues in the lateralization of a broadband signal was investigated using regression analysis. The stimuli consisted of eleven 1-ERB-wide noise bands (442 Hz-5544 Hz) containing ITD or ILD cues. In experiment 1, ITDs or ILDs were applied to the noise bands and roved independently on every trial. In experiment 2, the noise bands centred at 442 Hz and 5544 Hz were removed to investigate the effect of stimulus bandwidth. In experiment 3, the same two noise bands were present, but contained uncorrelated noise, reducing the effective bandwidth of binaural information. The results show that the cue-bands with the lowest- and highest centre frequency received the highest weights, while the other bands are equally weighted. This indicates that these edge frequency bands play an important role in lateralizing sounds.