HRTF Sound Filtering
Dr. Dobb's Journal July 1997
AHead-Related Transfer Function (HRTF) is simply a filter you run the sound through, and there is a different filter for every location around your head. In practice, a table with a fixed number of HRTFs is used, and points are interpolated between the existing HRTFs. To measure an HRTF, you typically would place microphones in the ears of human subjects and measure the response to test signals placed on various points of a sphere around the head. A sound coming from behind the head will have different phase shift, amplitude, and frequency attenuations than a sound coming from a different position, like the front. A set of HRTFs measured from one person may not work very well on another, because their heads and ears are shaped differently, and hence have different transfer functions. Ideally, a 3-D sound library would include several sets of HRTFs, so that the end-user can pick the one that sounds best.
-- S.C.D.
Copyright © 1997, Dr. Dobb's Journal
