Re: Head movement (beaucham )

Subject: Re: Head movement
From:    beaucham  <beaucham(at)MANFRED.MUSIC.UIUC.EDU>
Date:    Sun, 18 Dec 2005 14:47:34 -0600

Al, Pierre, and all,

One thought that comes to mind is a substantial difference between
rotating the head and a moving sound source: Doppler effect. 
Moving sound sources, like flies, exhibit a great deal of Doppler, 
but I've never perceived it when moving my head. Maybe skaters who
rotate fast on the ice would, but it's not normal experience.

Another thought is that a virtual reality system implements an
HRTF in real time. If a sound source is simulated as stationary 
and you move your head, the system is supposed to monitor a head 
position detector and keep the illusion of the source stationary.

Jim Beauchamp
UIUC, Urbana, IL

Al Bregman wrote:
>From: Al Bregman <bregman(at)HEBB.PSYCH.MCGILL.CA>
>Date: Sun, 18 Dec 2005 00:58:36 -0500
>To: AUDITORY(at)LISTS.MCGILL.CA
>Subject: Head movement
>Comments: To: Pierre Divenyi <pdivenyi(at)ebire.org>
>
>Hi Pierre and List,
>
>In addition, as you move your head, the change in amplitude in the high
>frequencies, -- resulting from different positions of the ear relative to
>the head's shadowing of the sound source -- will be different for sound
>sources that are at different angles from the head.
>
>Physically, the rotation of the head affects the sound in a similar way as
>rotating the set of sound sources around the head.  However, we don't know
>whether the efferent motor signal plays a role, in the case of voluntary
>head movement.
>
>Best wishes,
>
>Al