Perceptual weighting of elevation localization cues across frequency

Spectral cues are thought to be of particular importance in the perception of the elevation of a sound source. While some work has been done on demonstrating the importance of individual frequency bands, the relative importance of bands across a wide range of frequencies has not been firmly established. To estimate this, we built a broadband signal consisting of seven 1-ERB-wide noise bands that could each be assigned to a different elevation. The frequency range was either from 1 to 16 kHz with 3-ERB-wide spectral gaps or a higher-resolution range from 3 to 12 kHz with 1-ERB-wide spectral gaps. On each trial, each frequency band was independently convolved with a randomly chosen personalized head-related transfer function from one of seven elevations (±60 deg, 15 deg steps). In a 1-interval, 2-alternative forced choice task, listeners were asked to judge whether the sound was perceived above or below a reference stimulus presented on the horizontal plane. Two azimuth angles at -15 deg and -45 deg were considered. Perceptual weights for each frequency band were then calculated using a regression analysis method. Results showed that listeners tended to weight the 6.5 kHz band the highest for both azimuth directions and frequency resolution conditions.