Binaural synthetic sounds using head-related transfer functions (HRTFs) often cause localization errors, particularly in front-back errors and lateralization. This study examines whether using multiple adjacent directional HRTFs in binaural sound synthesis, which ordinarily uses a single directional HRTF, can improve sound localization accuracy by enriching spatial cues. The results showed that using HRTFs of multiple adjacent directions on the horizontal plane for synthesis improved localization accuracy in the front-back direction. However, localization accuracy decreased in the diagonal direction. The improvement in front-back localization accuracy was due to a reduction in front-back error and lateralization. The decrease in localization accuracy in the diagonal direction was due to an increase in localization errors to adjacent directions. Therefore, using multiple-direction HRTFs is effective for binaural synthetic sound in the front-back direction, where localization errors and lateralization frequently occur.
Morikawa et al. (Wed,) studied this question.