[LAD] Attenuation of sounds in 3D space

From: JohnLM <johnlm@email-addr-hidden>
Date: Wed Jul 21 2010 - 23:07:10 EEST

Continuation of talk from
Re: [LAD] Floating point processing and high dynamic range audio

Simply Subject line no longer described the actual content.

On 2010.07.21. 20:19, Jörn Nettingsmeier wrote:
> On 07/21/2010 08:56 PM, JohnLM wrote:
>
>> If I code program to handle attenuation of sounds depending on their
>> source (emitter) position in virtual 3D space, I guess then there's no
>> simple way to relate the effect to real world.
>> How this is usually handled?
>
> you reduce the level with distance (amount depends on whether you are in the near or far field and whether you have a point, line or planar source), and attenuate the high frequencies to simulate air damping. if you're in an enclosed space, you'd also want to take into account the dry-to-reverb ratio, and ideally simulate correct early reflections.

Thanks! Though this is quite sophisticated. I currently only worry about
sound (pressure) level. I will try to implement the rest when the
current code actually works.

Well I have a set of (omidirectional) point sources.
The code currently has no information whenever given space is open or
enclosed. (I guess open or empty space is implied then)

As much as I can understand the sound pressure is inversely linearly
correlated to distance. p~(1/d) or p=k*(1/d) where k is currently
undefined constant coefficient.

What's the thing about far and near fields?

On Wed, Jul 21, 2010 at 2:01 PM,<fons@email-addr-hidden> wrote:
> An audio signal represents pressure variation as a function of
> time. Multiplying it by two will give 2 times the pressure,
> and 4 times the power. The subjective result is another matter.
>
Ummm... is it sound pressure or sound pressure level? Or it doesn't
matter? (are they equivalent?)

On 2010.07.21. 20:40, Ralf Mardorf wrote:
> I guess the transit time issue for analog isn't solved. When I worked
> for Brauner we and SPL developed a surround microphone + SPL mixing
> console. IMO it's pure bullshit.
>
> http://audio.uni-lueneburg.de/seminarwebseiten/audiomedien/frst/material/ICA5.jpg
> http://audio.uni-lueneburg.de/seminarwebseiten/audiomedien/frst/material/asm5.jpg
>
> Perhaps today there is math for virtual effects, I don't know, but I
> would be very sceptic.
>

I'm sure any digital alogrithm are far from perfect to represent the
acoustic attenuation (and related) effects like in real world. But it
just need to be close enough.

Ummm... I somehow fail to see how the microphone rig is related to this.
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Received on Thu Jul 22 00:15:04 2010

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