OpenAL for iPhone does not support HRTF.

HRTF is the head related transform function used in three dimensional audio that models the shape of the head and ears. HRTF basically enables a low pass filter when the sound source is behind you making it sound as if... it were behind you.

In oalTouch (Apple's OpenAL demo source) the sound is the same when the source is either behind or in front of the listener. This seemed strange so I reported it as a bug to Apple (Problem ID: 6576577 in fact). I also noticed that the same problem exists on the Mac OSX Cocca native with the PIGE-OpenAL demo.

Got my answer today... "Engineering has determined this issue behaves as intended based on the following information: Please note that OpenAL doesn't support HRTF rendering."

This is disappointing. It means OpenAL only supports fading left to right and volume. It doesn't really take advantage of all the 3D positioning information. The phone certainly has the horsepower to do the computations for HRTF.