Common-acoustic-poles/zeros approximation of head-related transfer functions

Common-acoustic-poles/zeros (CAPZ) approximation is a more efficient way to model head-related transfer functions (HRTFs). In CAPZ approximation, a group of HRTFs can share a set of poles but use their own zeros. Previous CAPZ works, such as the Prony, Shanks and iterative prefiltering methods, were all based on the linearized least-square criterion. A new state-space approach, jointly balanced model truncation, is proposed by using singular value decomposition of a joint Hankel matrix. The proposed approach can choose the suitable order of IIR filters for HRTFs approximation according to the distribution of singular values but previous works can not. The proposed method is also modified to permit different orders for the poles and zeros. Computer simulations of these approaches are included for comparison.