Abstract:

The head- related transfer functions (HRTFs) which can be measured through experiments,usually dis-tribute in discrete directions,and the other HRTFs in unmeasured directions,have to be estimated by means of spatial interpolation.The commonly- used interpolation methods include the adjacent linear interpolation,the global interpolation,the bilinear interpolation,and the spherical- triangular interpolation.In practice,potential subjects' head movements in the HRTF measurement may result in error,thus influencing the accuracy and stability of the spatial interpolation.In this paper,the errors caused by slight head movements in the HRTF measurement are eva-luated,and the effects of the head movements on the above four kinds of spatial interpolation are compared by calcu-lating the signal- to- distortion ratio.The results indicate that,the global interpolation outperforms the others before and after the head movements,and is of excellent performance in a certain frequency band range of HRTF and with appropriate head movements.Due to the similarity of the HRTF spatial interpolation to the signal panning or mixing methods for the multi- channel sound,the proposed methods and the corresponding results are extended to analyze the stability of the sound image reproduced from the sound field signal mixing with 6 or 8 horizontal uniformly-arranged loudspeakers below 1.5kHz.

Key words: head- related transfer function, spatial interpolation, multi- channel sound reproduction, stability