RE: spatalization - octo 'appearances' in stereo


Subject: RE: spatalization - octo 'appearances' in stereo
From: Richard Wentk (richard@skydancer.com)
Date: Thu Jul 08 2004 - 12:39:29 EDT


At 11:44 08/07/2004 -0400, you wrote:

>you can use low-pass filters to simulate 3D locations: for instance, if
>you filter out a lot of the high frequencies in the left channel and leave
>the right you can get interesting results on headphones. in ideal
>conditions this would give the impression that the sound is "behind" you
>on your right. the other thing too is experimenting with adding a very
>slight delay to one channel (not an echo... but actually like a 1-25ms lag)

There's quite a bit of literature out there about various spatialisation
techniques. Roland invented a system called RSS about ten years ago, which
is still used in some of their processors. Many game soundcards use these
techniques for a more immersive effect, but you need some fairly advanced
programming skills to access them.

Probably the most effective system is Ambisonics. See some of the links at
www.ambisonic.net, especially to York University.

I stumbled across an astonishing effect playing back an RSS recording
through a mastering processor. The RSS processed vocals coming from the
studio monitors sounded like they were coming from right next to my ear. I
have no idea what was happening there, but it would be very interesting to
find out. There's a lot more research that could be done in all of these
areas.

>and perhaps using inversion...one inversion-related trick that i
>discovered through using cool edit pro's "channel mixing" feature
>;-) (laugh all you want). By mixing a bit (10% - 50% of the original
>volume) of an inverted right-channel signal into the left, and a bit of an
>inverted left-channel signal into the right channel, you can achieve a
>widening effect, which can be quite effective. due to cancellation, this
>can either making the sound louder or quieter, but it can still be quite
>effective.

This is an ancient technique. :-) Cheap stereos and cassette players would
often have a 'wide' switch that did exactly this.

It's not good for anything that requires mono compatibility. (But that's a
lot less relevant now than it was back then.)

Richard



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