Abstract: The measured value of pinna rotation angle depends on subject's original head position,and the corre- sponding measurement methods of pinna rotation angle may affect the distribution of individual head-related transfer functions (HRTFs) in various elevations.In this paper,both face-based vertical reference plane and Frankfurt refe- rence plane are used to measure and compare the pinna rotation angles of 60 human subjects,and a mean diffe- rence of about 5° is obtained.Then,in order to discover the effect of pinna rotation angle on the spatial distribution of individual HRTFs,the left pinna is rotated on the same ellipsoidal head model with an interval of 5°,and three calculation models respectively corresponding to the pinna rotation angles of 16°,11° and 6° are obtained.Moreo- ver,the HRTFs of the three coupling models are calculated and analyzed by means of the fast multi-pole boundary element method (FM-BEM). The results show that the frequency discrepancy of the pinna notches at high frequen- cies reaches about 1.0kHz,and that the magnitude difference even reaches about 10dB in some directions.In ad- dition,from the individual HRTFs customized via spatial coordinate transformation,it is found that the frequencies and magnitude of pinna notches of the customized HRTFs are similar to those of directly-calculated HRTFs,which means that the proposed individual customization method for individual pinna rotation angle is effective.

Key words: head-related transfer function, pinna rotation angle, Frankfurt plane, coupling model