Natural Science Forum / Physics / Acoustics / May 2007

    RPG devices are aimed at producing a great deal of diffusion at all
frequencies, but that may not be what is needed in a particular room.
Especially when diffusion is needed at frequencies below a few hundred
Hz since RPG diffusers are not very big.

    I suggest you investigate what your hall lacks in terms of diffusion,
if any is needed, then find diffuserobjects and methods that suit that
frequency range. As acoustics spans many octaves, the objects required
to produce diffusion at such frequencies will vary widely in size and
even appearance. Columns, niches, windows, furnture and odd walls serve
to diffuse low frequency sound, for instance.

    Note that the Freiburg hall repair includes "mobile elements", large
enough to diffuse lower frequencies .

    Modern "diffuser" manufacturers easily see the futility of attmpting to
package and sell diffursers for the lowest frequencies. In that case, it
is the responsibility of the consultant to ptovide the geometric design
of the elements required for diffusion. Then the carpenters and general
contractors serve to build them.

Hadi,

Angelo mentioned that you have a hall to treat, but I saw nothing about that
in your post. Regardless, I find the idea of adding resonance to a listening
room, as suggested on that site, to be the wrong approach. The usual
treatment goal for smaller rooms as shown in the photos on that site is to
remove resonances, not add them.

Can you can explain more about what you're trying to accomplish? And what
size room and the purpose too please.

--Ethan

These products appear to me to be intended for use within close
proximity to a sound source.  Their use above or behind an orchestra,
musical group, soloist, or talker would appear to be the intention.
Which, IMO, is what they should be restricted to.  Their pictures of
the use of these panels in office environments is a little suspect as
that would be a (IMO) bad application.

Incorporating such panels into a concert hall, recital hall, or even a
large studio recording room would not be a bad thing.  Though I would
doubt that they would serve as a stand-alone solution to any room
acoustics problem.  I.e., other treatments such as acoustical
absorbers and diffusers should also be considered for these
applications.  Of course, it would seem to me that the same effects -
at possibly reduced cost - would be achievable with off-the-shelf
decorative wood panels incorporated into, e.g., an orchestra shell
design that's facilitated by an experienced acoustician.

Diffusors could also provide enhanced performance in the same sorts of
applications.

I don't think a direct comparison can be drawn to RPG's Modex brand
since the latter are specifically designed as "bass traps."

My $0.02.

Savant