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Re: Spaces with unusual acoustics, long reverb, echo's etc.

Subject: Re: Spaces with unusual acoustics, long reverb, echo's etc.
From: "Rob Danielson" danielson_audio
Date: Sun Dec 30, 2007 12:25 am ((PST))
  At 1:05 PM +0000 12/29/07, riluttante wrote:
>Hi everyone,
>
>I'd love to hear some of your recommendations/rumors about locations
>with unusual
>acoustics, long reverb, echo's etc.
>Doesn't matter where they are.
>
>Does anyone know which space has the longest reverb in the world?
>
>Does anyone know of places with unusual, directional echo's such as
>large marble domes etc?
>
>I'm particularly interested in spaces where the sound changes
>dramatically depending on the
>listener's position in the room, such as domes with a strong "focal
>point" type echo in certain
>spots.
>This is a fascination of mine, and I'm hoping to be able to visit
>some interesting sites...
>
>Sources/forums for further information about this topic would also
>be highly appreciated.
>
>Thanks very much for any suggestions!
>Alex
>

Hi Alex--

Animals (including humans, of course) make constant use of
reverberation in their communications and navigations. Some
recordists focus a great deal of attention towards capturing and
understanding how local acoustics could be impacting the recordings
they make.

Nature recordists tend to have different appreciations of
"reverberation" than traditional, acoustic models. For the most part,
they interact with subtler forms of reverberation than recordists who
work almost entirely within enclosures.  The minimum requirement for
reverberation might be described as some percentage of the generated
sound waves being reflected several times before decaying or
escaping.  The space or location need not be as "enclosed" as one
might initially think. A stand of trees, the canopy of leaves or the
slope of a river bank can reflect nearby sound sources and create one
or more, quite distinct echoes. Low frequency sounds can be powerful
enough to reflect back and forth between modestly-profiled surfaces
that are as much as a mile apart.  The physical structure of land and
plant forms can lend resonance to a natural soundscape just as shape
influences a musical instrument, concert hall or cathedral. I had the
pleasure of hearing fireworks detonated at the end of a river valley
where I frequently record this past summer. The pronounced tones
created within the reverberations were hauntingly familiar to me.

I agree that long duration reverberations can feel extraordinary--
ethereal and almost limitless-- but even those 50 milliseconds or
less can also feel sublime.  There are aesthetics within
reverberation that merit wider exploration, documentation and
description.  When one begins to record sound widely, the possibility
of recording a sound source without the signature of a space or
enclosure can seem pointless.  There is always space. I like to think
of stereo and surround recording as 3D imaging and taking local
reverberations into consideration plays a large role in finding
useful mic positions. .

As far as scouting prime locations, surprises abound in just about
any area carefully probed, inside or out.  As you might imagine,
locations with lower ambient background sound levels can reveal more
subtlety.  Its common for the character to vary considerably when the
location of the sound source and/or listener change.

As for readings about reverberation in natural realms, I recently
came across some on-line research by Brian Mitchell concerning
coyotes' uses of reverberation in conveying location.  I wish I knew
of more studies concerning natural reverberation phenomena to
recommend. One can find plenty to read about synthesizing
reverberation and libraries of impulses from famous sites by
searching "IR convolution."  Rob D.



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