Distance localization using nonindividualized head-related transfer functions

Abstract

Past research has suggested that virtual auditory displays are most accurate when implemented using individualized head-related transfer functions (HRTFs). Directional localization accuracy, for example, is often substantially degraded when nonindividualized HRTFs are used, due to the resulting distortion of spectral cues to sound source direction. Although equally important for accurate spatial representation, little is known about distance localization accuracy in virtual auditory displays, and specifically, whether individualized HRTFs are necessary for accurate distance localization. Here, distance localization accuracy was assessed for six listeners, using both individualized and nonindividualized HRTFs in separate blocks of trials. The virtual sound sources were produced from special HRTF measurements (source distance ranging from 0.3 to 13.8 m) that also contained the acoustic transfer characteristics of a semireverberant room environment. This provided listeners with additional acoustic cues to source distance, including the ratio of direct-to-reverberant sound energy. Since no significant differences were observed in listener’s judgments of apparent sound source distance in the two stimulus conditions, it is concluded that distance localization accuracy, and degree of sound source externalization, do not depend on the use of individualized HRTFs when natural reverberation is available to the listener. [Work supported by NIH-NIDCD, NASA, and NIH-NEI.]