[Openal] Directional source acoustics
dpeacock at creativelabs.com
Thu Aug 16 10:50:10 PDT 2007
A few comments from the acoustic experts at Creative ...
I believe this is likely to be caused by the early reflections, and would
not occur in an anechoic room.
In a non-anechoic room, source orientation also affects the energy of the
individual early reflections. The early reflections fed by the "front"
radiation of the source will be louder, and their incidence at the listener
will be from the walls or obstacles that the source is facing. If the
early reflections are strong enough (walls close to source), this may
produce an illusion of movement of the source when the orientation of the
source rotates from side to side, even though the source position actually
does not change.
The EAX extensions to OpenAL include some features for enhancing the source
orientation model ....
A directive source radiates less energy into the room (this feature is 'on'
A directive source can have reduced (outside) volume at high frequencies
(controlled by an Outside Volume HF parameter)
Creative Labs, Inc.
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Re: [Openal] Directional source
If I'm imagining your setup correctly, no, it's not necessarily true
you should hear sound on the right side. Imagine if the speaker was a
mile away to your left. Rotating the speaker sideways isn't going to
make it sound like it's coming on your right.
I think you are expecting/referring to reflection off an (imaginary)
right side wall/barrier.
OpenAL doesn't do any reflection or obstruction. You would have to
model this yourself (or maybe vendor specific implementations have
extensions for this).
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