25 Apr
2007
25 Apr
'07
2:35 p.m.
Xavier Amatriain wrote:
On Wed, 2007-04-25 at 09:51 +0200, Joern Nettingsmeier
wrote:
> Jens M Andreasen wrote:
> i got a chance to listen to the wavefield synthesis system at tu berlin
> for several hours (thanks torben for a late-night session!), and i found
> that virtual sound sources inside the speaker array work very well for
> low and mid frequencies (torben had me step inside a techno bass drum,
> and it was quite astonishing), but it only works for higher frequencies
> as long as you're not in between the speakers and the virtual sound
> source (due to dampening i guess, and because the virtual source has not
> converged correctly yet).
I am really surprised that the most astonishing thing
in such a setting would be
a low freq bass drum. Actually this effect has little to do with
wavefield synthesis or even with the number of speakers and has more to
do with the law of physics. You can roughly get the same effect at low
frequencies with a properly tuned auditorium (like the one at TU) and a
few subwoofers placed in the right positions. Low frequencies have
wavelengths much longer than the interdistance between speakers and are
comparable to the distance to/from the listener. So there is no planar
wavefront here but rather a standing wave.
granted. but a bass drum does have hi-frequency cues as well. the
interesting thing about that drum was that there was an insane amount of
sound energy in a very small space, with very few and quite soft phantom
images.
Furthermore, the interesting thing about wavefield is
not *only* that
you can create an immersive sound field (provided, as has been
discussed, that you are not too close to any individual source) but also
that you can place a sound object in an *arbitrary* position. The guys
from IOSONO have a GUI in which you can place objects (tracks) in a
given position and even define trajectories over time.
yes you can, but my point was it does not work very well when you are
between the speakers and the virtual source, which does happen in a
large auditorium.
from my listening experience in the wfs room at tu berlin i can say that
sources outside the speaker array are far more stable and convincing
than those inside. that said, it's still amazing what you can do inside.
best,
jörn
(who is still fiddling to get decent 1st order ambisonics at home and
hasn't come very far yet...)
--
jörn nettingsmeier
home://germany/45128 essen/lortzingstr. 11/
http://spunk.dnsalias.org
phone://+49/201/491621
Kurt is up in Heaven now.