Head-related transfer function enhancement for improved vertical-polar localization.
Douglas S. Brungart, Griffin D. Romigh, Brian D. Simpson · The Journal of the Acoustical Society of America · 2009
Under ideal laboratory conditions, individualized head-related transfer functions (HRTFs) can produce virtual sound localization performance approaching the level achieved with real sound sources in the free field. However, in real-world applications of virtual audio, practical issues such as fit-refit variability in the headphone response and nonindividualized HRTFs generally lead to much worse localization performance, particularly in the up-down and front-back dimensions. Here we present a new technique that “enhances” the localizability of a virtual sound source by increasing the spectral contrast of the acoustic features that are relevant for spatial perception within a set of locations with nearly identical binaural cues (i.e., a “cone-of-confusion”). Validation experiments show that this enhancement technique can improve localization accuracy across a broad range of conditions, with as much as a 33% reduction in vertical-polar localization error for nonindividualized HRTFs measured on a KEMAR manikin; a 25% reduction in vertical-polar error for nonindividualized HRTFs measured on other human listeners; and a 33% reduction in vertical-polar error for individualized HRTFs presented under nonideal laboratory conditions (i.e., with headphone fit-refit variability). These results suggest that the proposed technique could provide benefits across a wide range of real-world virtual audio display applications. [Work sponsored by AFOSR.]