Re: [Algorithms] Spherical harmonics for room acoustic modelling

[Jon W. <jw...@gm...>]

You can calculate the impulse response of any environment analytically these
days.
The main problem is that it's really computationally expensive to apply a
very long convolution response to all sound.
Creative tried 10-15 years ago to drive up the compute power for sound, with
the Live! series (based on E-mu DSPs) and the (somewhat finicky) EAX API.
Another company, called Aureal, actually went a step further, and allowed
you to specify a crude representation of your geometry, but they died before
they could get mainstream traction.
However, what actually happened was that nobody cared, and sound is now just
a 50 cent DAC hooked to a raw DMA engine on the south bridge of the
motherboard, so any processing has to use that precious resource, the
very-expensive general-purpose core CPU.
Good luck telling your AI, rendering and physics people that you'd like 1/4
the CPU power for applying audio effects :-(

Sincerely,

jw


--
Americans might object: there is no way we would sacrifice our living
standards for the benefit of people in the rest of the world. Nevertheless,
whether we get there willingly or not, we shall soon have lower consumption
rates, because our present rates are unsustainable.



On Sat, Jul 17, 2010 at 12:09 PM, Oscar Forth <
os...@tr...> 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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