Head-related transfer functions are directional filters used to place sound in space.

Evidence

This type of processing is required in virtual-reality systems, in which sound sources need to remain associated with their visual cue. One way of achieving this is to measure the effective filter response to the two ears for different directions, as shown in Figure 7.14. These are known as head related transfer functions (HRTFs). — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2250

Categorization

• DEFINE: Defines HRTFs as the measured per-ear filter response for each direction.