Abstract:

In this paper,first,a combined model consisting of a spherical dodecahedral sound source and a spherical head model is established. Then,the binaural pressure and near-field head-related transfer function ( HRTF) are calculated via the multipole expansion of spherical harmonic functions and the rotation transform of spherical basis functions. Moreover,the common influences of the directivity and multiple scattering of the spherical dodecahedral sound source on the near-field HRTF measurement are analyzed according to the magnitude spectrum errors of HRTF. The results show that ( 1) the effects of sound source on near-field HRTF measurement weakens with the decrease in sound source radius and with the increase in half scan angle of each local pulsating unit; ( 2) when the sound source distance is not less than 0. 2m,the sound source radius is not more than 0. 025 m and the half scan angle is not less than 23. 6°,the errors resulting from the source generally appear at the frequencies more than 12 kHz; ( 3) except for some contralateral directions,the errors of HRTF are controlled within ± 3. 5dB,which basically satisfies the requirements of the near-field HRTF measurement. The proposed method is finally proved valid and applicable by the data measured in some particular directions with the help of a self-fabricated wood sphere and a practical spherical dodecahedron sound source.

Key words: spherical dodecahedron sound source, near-field measurement, head-related transfer function, multiple scattering, directivity