Trends in acquisition of individual head-related transfer functions

Abstract

Head-related transfer functions, HRTFs, that is, the pair of acoustic transfer functions from a sound source in anechoic space to the human ears, are important elements of binaural technology. In order to make practical use of them, fast and comfortable means for the acquisition of individual HRTFs are required and, furthermore, convenient data formats for their comprehensive representation are needed. This chapter first recapitulates early and seminal work in the field of HRTFs. From here, a concise picture of recent trends for spatially discrete and continuous measurement of HRTFs, with a focus on the more recent continuous, that is, dynamic approach, is developed. For the continuous method, latest results regarding the optimization of the loudspeaker excitation signal for the measurement are presented. With respect to HRTF representation and usage, the chapter refers to spatially-discrete databases in time- or frequency-domain and, additionally, to the spatial Fourier-series domain. The latter constitutes an ideal basis for both interpolation and extrapolation of discrete data as well as for the representation of the results of spherically-continuous measurements.