Spectral HRTF enhancement for improved vertical-polar auditory localization

Head-related transfer functions (HRTFs) can be a valuable tool for adding realistic spatial attributes to arbitrary sounds presented over stereo headphones. However, in practice, HRTF-based virtual audio displays are rarely able to approach the same level of localization accuracy that would be expected for listeners attending to real sound sources in the free field. In this paper, we present a novel HRTF enhancement technique that systematically increases the salience of the direction-dependent spectral cues that listeners use to determine the elevations of sound sources. The technique is shown to produce substantial improvements in localization accuracy in the vertical-polar dimension for individualized and non-individualized HRTFs, without negatively impacting performance in the left-right localization dimension.