Re: [LAD] Attenuation of sounds in 3D space

On 2010.07.22. 1:30, fons@email-addr-hidden wrote:
> On Wed, Jul 21, 2010 at 10:07:10PM +0200, JohnLM wrote:
>
>> What's the thing about far and near fields?
>
> The rule pressure = 1 / distance is true only for
> theoretical point sources, and for real sources if the
> distance is much larger than the size of the zource.
> In the other case you are in the 'near field' where
> things can get quite complex.
>
> For some sounds you are almost always in the 'near' field
> e.g. a highway with many moving cars on it, the seashore,
> etc. These are essentially large line sources with many
> independent sound generators which blurr into a single
> sound, and in that case you'd get different relations,
> e.g. pressure = 1 / sqrt(distance).
>
>> 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?)
>
> The term 'sound pressure level' (SPL) usually refers to sound
> pressure measured in a standardized way.
>
> What you try to do is called spatialization. It involves
> modelling the directivity and motion of the sources and
> their interaction with the space they are in, and it can
> get arbitrarily complex.
> Software to do this in specialised cases (e.g. electronic
> music) exists. More general solutions and in particular
> practical systems (allowing complex and dynamic scenes)
> are still a research topic, e.g. at Barcelone Media.
>
> Ciao,
>

I may have bitten more than I can chew on. :)

Currently I seek to make "stupid" solution. Something like the way every
decent game engine does it.
Except my solution is going to be non-realtime and not (sound) hardware
dependent. I reckon something like this already exist in FOSS, but I
haven't been able to find anything (I have no time examining code of
every other audio project out there).

Thanks for the info. Good to know I'm heading the right way. Indeed
'near field' sound sources were ones I never actually gave much thought
on their implementation in software. This will go next on my TODO list.

Regards,
John
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Received on Thu Jul 22 16:15:02 2010