[LAD] A Cathedral in your backyard

[Joern Nettingsmeier]

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

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Kurt is up in Heaven now.