A comparison of head related transfer function interpolation methods

In order to achieve realistic synthesized 3-dimensional acoustic fields over headphones, low-order approximations of head related transfer functions (HRTFs) are desirable not only because of the computational complexity reduction, but also because of the potential for allowing listeners to modify the low-order approximation parameters in order to generate interpolated HRTFs that optimize the source localization percept. By fitting the directional component of a HRTF, commonly known as the directional transfer function (DTF), it is possible to achieve low-order systems for the purpose of interpolating HRTFs even if the number of parameters required to approximate the entire HRTF is relatively large. The present paper compares the relative performance of interpolation methods for both all-zero and pole-zero modelling of the DTFs. With the goal of developing better interpolation methods by incorporating subjective preferences, active sensory tuning (AST), which has been previously shown to provide an efficient means of searching through moderate dimensional parameter spaces using subjective feedback, is proposed as a method of providing high quality interpolated DTFs within reasonable time constraints.