Predicting the Precision of Elevation Localization Based on Head Related Transfer Functions

While the human hearing capability for horizontally localized sound sources is mostly based on binaural cues, the localization of elevation along the "cones of confusion" can only rely on spectral cues provided by the directionality of head related transfer functions (HRTF). This paper explores how the magnitude of spectral differences between HRTF affects the availability of spectral cues to perceive and detect different elevations and hence limits localization accuracy. A method to predict localization accuracy is presented, based on analysis of the gradient of HRTF log-spectral differences for elevation positional changes. To this end, the localization accuracy is estimated from an HRTF database with 45 subjects. Validation of the results shows good agreement with results from subjective localization experiments reported in literature.