On the Influence of Continuous Subject Rotation During High-Resolution Head-Related Transfer Function Measurements

In recent years, the required time for high resolution individual head-related transfer function (HRTF) measurements has been reduced by the use of microphone or loudspeaker arrays and with parallelization of measurement signals. While a short measurement time is beneficial during HRTF measurement of any resolution, it is essential for the acquisition of high resolution individual HRTF measurements since subjects cannot remain motionless over extended periods of time. This decrease in measurement time can be achieved by using continuous rotation during the measurement, instead of step-wise subject positioning. This paper examines the influence of such continuous measurement rotation with sine sweep measurements and the necessary subsequent post-processing. The goal is to identify a rotation speed, from a predefined set of speeds, that does not have an audible influence on the measured HRTF itself. To this end, a subjective and objective comparison between the two measurement modes is presented in this paper. Five HRTF measurements of an artificial head are acquired using different rotation speeds. They are compared objectively to a reference measurement of the same head performed with step-wise measurement rotation in the same measurement setup. A subjective listening experiment examines whether the found differences between the measurements do result in an audible difference. The objective evaluation showed expected trends regarding the dependency of the error on the measurement speed and is used to validate the used signal post-processing. The subjective evaluation showed that with a rotation of 3.8°/s no audible differences to the reference are present.