On Tue, 06 Dec 2005 20:29:35 GMT, "PipeDown"
wrote:

Two layers of plastic with an air gap (vented away from quiet area) will
significantly reduce the noise over one sheet



"Michael Daly" wrote in message
. ..

On 6-Dec-2005, "3D Peruna" wrote:

"mulderig" wrote in message
...
It is sold at both of those stores. The Luctite is more expensive then
the
acrylic. I recently both a 6 x 4 foot sheet of the Lexan for about $57.
You can get cutters to cut it to the correct size for about $2.00 or
you
can have the store do it for you.

All the best,
M.


Just don't use a laser to cut lexan...

You can cut polycarbonate (generic name for Lexan) with woodworking tools.

http://www.sheffieldplastics.com/web_docs/Makrolon_Fabrication_Guide.pdf


I can add something to that. From the Naval Facilities
Engineering Command (U.S.) comes the "Architectural
Acoustics; Functional Requirements Design & Technology"
design manual 1.03, dated May, 1985.

From page 27:

.... Double-glazed units are no better [for sound insulation]
than single-glazed if the air space is 1/2 inch or thinner.
This is due to a resonance condition created by a close air
coupling of the glass panes. This type of glass should be
avoided near truck, train, or aircraft noise. A 2-inch
(50mm) airspace between glass panes will provide better
noise reduction.

*****

Oddly enough, the manual doesn't talk about acrylic windows,
something that should have been widely available in 1985.

The acrylic is much lighter than glass, of course, and may
offer less "mass-resistance" to deaden sound. Or, it may
have some other property that is better at absorbing
sound--I don't have any data quick at hand for that. But
you're probably not going to consider glass, under any
circumstance, for an over-head application.

I would think that the larger air space between panes would
apply to acrylic, as well, to attenuate accoustic coupling.


For the windows on my house, I simply installed double pane
windows in pairs--one window set on the outside, and one on
the inside, with mini-blinds in-between. I did all the
"outside" windows first, and noticed quite an improvement
over the original steel-framed casement windows. But when I
put the "inside" window-sets in, the noise reduction was
truly uncanny! Now, when there's a lot of traffic on the
street, opening just the inside window changes the
sound-level so much that it "feels" like opening a window in
a normal house. Then, if also open the outside window the
traffic noise blows my hair back (well, what hair I've got
left to blow back!).

Any house that I buy and live in, that has excessive
exterior noise, will get that treatment in a heart-beat!

I trimmed the inside window-sets with 1 x 4 white oak, and
attached the trim with countersunk, electroplated (yellow,
whatever it is) deck / drywall screws, and just let the
heads show. I think it looks nice.

--
tbl