A COMPUTATIONAL THEORY OF SPECTRAL CUE LOCALIZATION

This paper presents a computational theory of localization based on analysis of the cues contained in the spectrum received at the eardrum. It is well established that monaural localization, and binaural localization onto the cone of confusion, for pure tone stimuli are unrelated to the actual source position. On the other hand, broad spectrum stimuli are localized with some accuracy. This paper outlines the properties that the operations performed on a received spectrum must have in order for the source to be localized accurately. The use of the two simplest nontrivial such operations, the first and second finite differences of the spectrum, respectively, are explored in detail. This analysis shows that so long as the spectrum of the sound source has a locally constant slope, accurate localization using such operators is possible. A simulation of the localization process making use of measured human head-related transfer functions (HRTF's) and two recorded spectra demonstrates that the second-order finite difference operator produces much more accurate and robust estimates than the first-order operator.