Re: multi-channel list/problems


Subject: Re: multi-channel list/problems
From: Philippe-Aubert Gauthier (Philippe-Aubert.Gauthier@USherbrooke.ca)
Date: Tue Nov 16 2004 - 14:22:24 EST


In comparison with other WFS systems, the one at IRCAM (which use planels in the
front) have seems to be more appreciated because it is more "soft" than WFS
with electrodynamics loudspeakers. But the cheaper implementation with
loudspeakers still sound very promising (based on my experience). On the other
hand, less visually prominent speakers, like the panels, reduce the risk of
visual influences (vision is a so bad boy!).

You can do some sort of WFS by yourself. To reduce the computational power, you
may only need N sources (omni in low freq.), N channels, N amp + N microphones
(bidirectional in low freq.) and that's it, you get a WFS system ... which, in
this case, you may call "holophony".

As an example of this last affirmation, take a look at Edwin van der Heide
installation which is precisely WFS reproduction with WFS sound capture :

http://utopia.knoware.nl/users/heide/world_beyond.html

I am currently trying to make a preliminary Pure-Data light patch for WFS, like
little 8-channels module. But its quite demanding and I don't have too much
time ... my goal with this is to show that you can approximate WFS with free
(yeah!) DSP tools like PD.

Selon Steven Naylor <steven.naylor@sonicart.ca>:

> > --- Greg Eustace <g_eustac@alcor.concordia.ca> wrote:
> >...
> >> I also have a question. In multi-channel situations, there is
> >> the problem of the sweet spot being smaller than the seating
> >>area. Can anyone point me to any previous research that is
> >aimed >at widening/optimizing the size of the sweet-spot?
> >...
> >
> >You may want to look at Wave Field Synthesis. It claims to
> >eliminate the problem of the sweet spot, although I have never
> >had the chance to experience it myself. Have a look:
> >
> >http://retiary.net/idea/idea7/idea_7/marijeb/marije.htm
> >
> >best,
> >
> >Aki
>
> I recently listened to a lengthy demo of a Wave Field Synthesis
> system installed at Ircam, and it was amazing. I don't pretend to
> understand what's going on (yet...!) but the imaging is superb and
> stable from just about anywhere in the room. Their installation used
> a series of flat-panel multispeaker units mounted at ear level, so
> there were limits to the vertical range - but I'm sure that's
> simply a limitation of this installation.
>
> There's a (small) image of it here (be sure to copy the entire URL if
> it line-breaks):
>
> http://www.ircam.fr/50.html?&L=1&tx_ircam_pi4[showUid]=2&ext=4
>
>
> The processing power it requires does seem substantial, and those
> flat-panel arrays are not cheap....... but the potential for both
> listening rooms and concert spatialisation is very exciting.
>
> S
> --
>
> Steven Naylor
> Composer / Producer
>
> http://www.sonicart.ca
>
>

%====================================================================%
% Philippe-Aubert Gauthier, B.Ing, M.Sc. %
% Étudiant au doctorat en reproduction de champs acoustiques %
% %
% GAUS (Groupe d'Acoustique et de vibrations de l'Université de %
% [ Sherbrooke) %
% CIRMMT (Centre for Interdisciplinary research in Music, Media %
% [ and Technology) %
% %
% http://www3.sympatico.ca/philippe_aubert_gauthier/acoustics.html %
%====================================================================%



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