90-06/binaural.stereo.work From: "Michael John Muuss " Subject: Re: Binaural stereo Date: 17 Jun 90 03:20:09 GMT Organization: Ballistic Research Laboratory In article , aj14+@andrew.cmu.edu (Andrew David John) writes: |> |> If a computer could reproduce the echo/frequency-shifts/etc... that occur |> when sound comes from a given direction and passes by the head, then it |> could breate synthetic binaural stereo. |> |> Does anyone know if the positioning mechanisms of the human auditory system |> are understood? I refer everyone to the excellent work being done at NASA/Ames by Elizabeth Wenzel and Scott Foster. I saw their equipment demoed at the 1990 Symposium on Interactive 3D Graphics (Snowbird Utah, March 1990), and the audio effects were very well done. Their aparatus was a Sennheiser HD-540 Pro headphone with a Polhemus 6 DoF tracker cemented to it, and another 6 DoF tracker for you to hold. A PC & a snazzy custom DSP board took a monaural sound source (in the demo, from a CD player) and positioned it to "seem" like it was located at the hand-held tracker. Move either your head or the tracker, and a pretty good approximation of the "right" effect happened. The Head-Related Transfer Function (HRTF) is synthesized from 144 pairs of Finite Impulse Responses (FIRs) measured for the sample head. Superb work. Read about it in COMPUTER GRAPHICS, V 24, Number 2, March 1990 "A publication of ACM SIGGRAPH, special issue on the 1990 Symposium on Interactive 3D Graphics". pp 139-140. Best, -Mike Muuss Advanced Computer Systems Ballistic Research Laboratory APG, MD 21005-5066 ===== Blauert, Jens, 1983. _Spatial Hearing: The Psychophysics of Human Sound Localization_, Cambridge, MA: MIT Press Wenzel, Elizabeth M. 'Localization in Virtual Acoustic Displays,' _Presence_ 1st issue. Wightman, F.L. & Kistler, D.J. 1989a,b. 'Headphone Simulation of Free-field Listening I, II.' _Journal of the Acoustical Society of America_, _85_, 858-878.