Fwd: Spherical harmonics for room acoustic modelling

I got this mail direct to my e-Mail so I've forwarded it to the mailing list
:)

Thanks Stephen.  VERY interesting post :)

---------- Forwarded message ----------
From: stephen mccaul <[email protected]>
Date: 17 July 2010 21:44
Subject: Re: [Algorithms] Spherical harmonics for room acoustic modelling
To: [email protected]


My list response bounced. silly email addresses.

So i will send it to you directly.



http://en.wikipedia.org/wiki/Ambisonics

uses spherical harmonics to compute a 3d approximation of the pressure about
a point.

There are a variety of people working on real time room response technology.

Here are a few papers:

http://www-sop.inria.fr/reves/Nicolas.Tsingos/publis/ntsin_aes35_reverb.pdf
http://www.aes.org/e-lib/browse.cfm?elib=15157
http://www.mee.tcd.ie/~gkearney/ResearchPapers/Masterson_Kearney_and_Boland_AES35_Submission


Its a bit expensive to run a convolution per voice given today's consoles
(maybe on the ps3 or if you wrote
your own decoder so you can keep the signal in the frequency domain from the
get go.





Oscar Forth wrote:

> I will admit first off I don't have a great knowledge of things like
> Pre-computed Radiance Transfer but I was having a chat with a colleague
> recently on how audio research lags behind video research in gaming.
>
> One idea that we were talking about is using spherical harmonics in a
> similar way to PRT to do some sort of Pre-computed Acoustic Transfer.
>
> Basically you'd add a new material type to a room that would give you the
> sound reflectivity of a given surface.   You could then use the same
> techniques (obviously calculated with something like OpenCL) to give you a
> good model of how sound moves round a room.  Has anyone done anything like
> this?
>
> It kinda struck me that you'd be able to model things like acoustic
> reflections off a hard surface, acoustic dispersion from soft surfaces as
> well as getting things like occluders thrown in as a bonus.  Add to that
> you
> could use the same techniques as are used for translucent surfaces to model
> sound transfer through a surface and the slight bending of audio round
> corners.
>
> Are there any papers on the subject at all?  It struck me as something
> worth
> finding more out about as it would give the ability to create truly rich
> sound scapes with very little actual fiddling needed to get it right.
>  You'd
> just pass the model through your PAT calculation engine then play sounds
> and
> get them playing right.
>
> Any thoughts?
>
> Cheers!
>
> Oscar
>
>
>
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