Spectral Weighting of Monaural Cues for Auditory Localization in Sagittal Planes

Localization of sound sources in sagittal planes significantly relies on monaural spectral cues. These cues are primarily derived from the direction-specific filtering of the pinnae. The contribution of specific frequency regions to the cue evaluation has not been fully clarified. To this end, we analyzed how different spectral weighting schemes contribute to the explanatory power of a sagittal-plane localization model in response to wideband, flat-spectrum stimuli. Each weighting scheme emphasized the contribution of spectral cues within well-defined frequency bands, enabling us to assess their impact on the predictions of individual patterns of localization responses. By means of Bayesian model selection, we compared five model variants representing various spectral weights. Our results indicate a preference for the weighting schemes emphasizing the contribution of frequencies above 8 kHz, suggesting that, in the auditory system, spectral cue evaluation is upweighted in that frequency region. While various potential explanations are discussed, we conclude that special attention should be put on this high-frequency region in spatial-audio applications aiming at the best localization performance.