Introduction to Head-Related Transfer Functions (HRTFs): Representations of HRTFs in Time, Frequency, and Space

In this tutorial, head-related transfer functions (HRTFs) are introduced and treated with respect to their role in the synthesis of spatial sound over headphones. HRTFs are formally defined, and are shown to be important in reducing the ambiguity with which the classical duplex theory decodes a free-field sound's spatial location. Typical HRTF measurement strategies are described, and simple applications of HRTFs to headphone-based spatialized sound synthesis are given. By comparing and contrasting representations of HRTFs in the time, frequency, and spatial domains, different analytic and signal processing techniques used to investigate the structure of HRTFs are highlighted.

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