25 Apr
2007
25 Apr
'07
2:22 p.m.
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.
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.
Again the main issue with wavefield synthesis is the sweetspot (i.e. as
soon as you get close to the sources/speakers the effect starts to
crumble). But as long as you can have this under control the kind of
effects you can accomplished are way beyond being inside a bass drum
(not that the sweetspot in places like cinemas, the Allosphere or even
in your living room is ideally limited so listeners are not too close to
the sources).
--
/*********************************
* Xavier Amatriain *
* Associate Director - MATi *
* Research Director - CREATE *
* UCSB, Santa Barbara CA *
* 1-(805)- 893 83 52 *
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