[LAD] Attenuation of sounds in 3D space

[Fernando Lopez-Lezcano]

On Thu, 2010-07-22 at 20:22 +0200, Ralf Mardorf wrote:
> On Thu, 2010-07-22 at 10:52 -0700, Fernando Lopez-Lezcano wrote:
> > On Thu, 2010-07-22 at 14:01 +0200, Ralf Mardorf wrote:
> > > On Thu, 2010-07-22 at 01:04 +0200, Arnold Krille wrote:
> > > > We are not talking about 5.1 or 7.1 here. These suck big time.
> > > > 
> > > > We are talking about ambisonics vs. binaurals vs. simple stereo here!
> > > 
> > > Ok, I noticed this.
> > > 
> > > Fon's AmbDec is the player for the files from
> > > http://www.ambisonia.com/?!
> > > 
> > > I guess a friend who lives near to my home has at least 8 outputs for an
> > > Envy24 sound card and at least a JBL 5.1 setup, so the 5.1 speakers
> > > could be used for a minimalist ambisonics.
> > 
> > Yes. Fons ships an ambdec configuration for playing in a 5.1 setup (it
> > is not optimal because the back speakers in a 5.1 setup are too far
> > apart but it works - I use it at home). Of course it assumes that the
> > 5.1 setup is correct. This link has a diagram of the speaker angles:
> > 
> >   http://de.wikipedia.org/wiki/5.1
> > 
> The speakers of the 5.1 system should just be used, because they are 5
> of the same type and because there are equal amps for the speakers.
> There's no need to keep
> http://upload.wikimedia.org/wikipedia/de/thumb/4/4e/ITUKreis_Ruhnke.jpg/300px-ITUKreis_Ruhnke.jpg, if the speakers should really be placed correctly for 5.1 at the friends living room at the moment.

I'm not sure I understand. The 5.1 ambisonics decoder in Ambdec can
decode to that arrangement and it is pretty good. You could try that
before moving the speakers around. 

> If possible I would prefer to replace them in a way that's good for
> ambisonics.
> ...
> IIUC 4 speakers could be set up in a quadrate with "front" at positiv-x
> direction and the listener has to be in the middle of the quadrate.

Yes, you could move them into a square, use only four and use the square
decoder. A 5.1 setup can be used to play up to second order ambisonics,
a 4 channel square can only play first order ambisonics. 

Most of the recordings in ambisonia.com are first order (but I think
there are a few higher order as well). 

See this for another example of ambisonics at home:

http://stackingdwarves.net/public_stuff/linux_audio/ambi_at_home/joern_nettingsmeier-ambisonics_at_home.pdf

-- Fernando



> Maybe there will be 8 similar speakers and amps, but regarding to the
> sound card the limit is 8 channels. I guess somewhere on the ambisonics
> website there will be some text and graphic about such setups.