Inter-Subject Differences of Head Related Transfer Functions

Abstract

Examination of the characteristics of individual Head Related Transfer Functions (HRTF) requires the use of a specific measurement setup and procedure. This paper describes the design of a far field HRTF measurement setup in which the subject is continuously rotated towards a sound source placed at a certain elevation angle. Currently the system allows for the acquisition of HRTF pairs (left and right ear) at 370 source positions in the surrounding space. The test signal is recorded by two miniature microphones placed at the entrance to the blocked ear canal. Completing of a set of HRTFs at all spatial positions takes about 45 minutes for one subject. The present measurement setup was evaluated by acquiring HRTFs with the use of an acoustic manikin and with the participation of subjects. The paper discusses inter-subject differences among measured HRTFs, both in horizontal and vertical planes, with reference to the results obtained with the use of the acoustic manikin.