HRTF Interpolation Through Direct Angular Parameterization

Under anechoic conditions, a system that generates 3D binaural sound should simulate the head-related transfer functions (HRTFs) that represent sound changes from the source to the listener´s ears. Such a system could directly use HRTFs measured over a sphere around the listener. However, since it is not feasible to perform measurements for every position, practical systems interpolate the necessary functions between measured HRTFs. This paper proposes a generalization of the continuous variable digital delay (CVDD) described in the literature, yielding a two spatial-variable dependent transfer function. It performs a polynomial interpolation whose coefficients are optimized on a region over the sphere, so that the angular coordinates of any point inside the region map directly into the corresponding HRTFs. Performance assessment is done through graphical means. The issue of continuity in moving sound generation is also approached, through the combination of adjacent-region structures