Design of a Fast Broadband Individual Head-Related Transfer Function Measurement System

In order to improve the quality of binaural based virtual reality systems, the use of individual headrelated transfer functions (HRTF) plays a major role. This paper presents a system for individual HRTF measurements developed at the Institute of Technical Acoustics in Aachen. The main characteristic of this system is the close distance between head and sound sources. This allows to make use of audible neareld e ects as well as to extrapolate the measurement result to di erent ranges with a small error. In this set-up the common fareld assumption of a plane wave incidence on the head is no longer valid and thus great care is taken to design a loudspeaker which radiates as similar as possible to an ideal point source in a wide frequency band (200Hz to 16 kHz). The supporting arc is constructed with thin metal sticks in a trellis structure in order to minimize disturbing re ections. Up to 40 loudspeakers can be positioned along the arc, allowing a exible choice of the employed measurement grid. A neck support is used to assist the person under measurement to stay at rest at the same position for the entire duration of the measurement, which should take no more than ten minutes to complete.