Optimization of spherical and spheroidal head model for Head Related Transfer Function customization: Magnitude comparison

Researchers have used a spherical head model to construct a HRTF (head related transfer function), which has a single adjustable parameter (radius of head) for HRTF customization mainly because of its simplicity. By using the mathematical form to calculate analytic spheroidal HRTF for an incident point source, a spheroidal head model can be used for near-field HRTF customization with two adjustable parameters (head width and head height). To see the necessity of head height consideration, two analytic solutions; spherical HRTF and spheroidal HRTF, are compared with a measured HRTF (KEMARpsilas HRTF). By varying head dimensions and ear offsets, notch frequency pattern is calculated. Through optimization procedure, we find an optimal parameters which minimizes notch pattern error between the estimated head notch pattern and notch pattern of measured HRTF. In the view point of magnitude of HRTF, performance of spherical head model and spheroidal head model is compared. Modeling error is reduced by using a spheroidal head model instead of the conventional spherical one.