Interpolation of head-related transfer functions by spatial linear prediction

Head-related transfer functions (HRTFs) are essential for creating a virtual sound source when sound waves are transmitted through headphones. The measurement of HRTFs is a complicated and time-consuming task. Therefore, the interpolation of HRTFs is crucial for virtual auditory display systems in which both listeners and sound objects are likely to move in a virtual auditory space. In this study, HRTFs are measured with a high spatial resolution in order to develop an effective interpolation method. An analysis of HRTFs indicates that the functions exhibit periodicity in amplitude along the azimuthal angle. The optimum filter coefficients required to interpolate HRTFs from several functions measured along multiple azimuthal directions are derived. Computer simulations indicate that in comparison to conventional methods, the proposed method yields less estimation error in the interpolation of HRTFs. Listening tests indicate that the proposed method can provide better perception of virtual sound.