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Soundproofing an apartment -----

Noral D. Stewart noral at ix.netcom.com
Sat Jul 25 00:19:42 EST 1998

Jon Held wrote:
> Hello! I have a soundproofing question.  My new apartment has a sound problem
> - there is an exhaust fan (from a restaurant) near my back door. Much of the
> sound winds up in my apt - mostly mid-range "whining".  It's loud, and
> frustrating.  I want to insulate the back of the apt (on the outside) with
> something.  There is a thin back door, a wall above it which is just 2 layers
> of thin plywood, and a skylight on the ceiling nearby.
> Which material would be best for blocking the sound-
> 1) Wood
> 2) Styrofoam, or
> 3) Standard white ceiling tiles (Don't know what they're made from -
> fiberglass?  I have a few unused ones)
> Any advice on this question or other tips on soundproofing greatly
> appreciated.
> thanks.
> -Jon Held

First suggest you post also to alt.sci.physics.acoustics.

Regarding the blockage of sound, wood is the best of the three materials
you mentioned.  Weight is the primary factor in sound blockage.  You can
then improve blockage by putting the weight in layers separated from one
another with a sound absorbing material (such as fiberglass insulation)
in the cavity between layers.  Styrofoam is acoustically worthless, too
light to block much, and not sound absorptive.  Ceiling panels are
primarly sound absorbers.  The prevent sound that hits them from
reflecting. Fiberglass ceiling panels provide very little sound
blockage.  Most ceiling panels are made of denser mineral fiber and
provide a little more sound blockage.

Now to your problem.  Whatever, you  do, try to figure out the primary
source of the problem first.  Try covering various areas with something
heavy and see what makes the biggest difference.  If no one area stands
out, two or more are probably about equal.  Eliminate all cracks first,
such as around the door.

If the door is very light and not well sealed, it is probably the
primary source of your leakage.  Consider replacing it with a solid core
wood door with good weatherstripping.  Next, close the outside air vent
on the air conditioner.  It is a direct opening to the outside.  How
thin is the plywood above the airconditioner?  Each doubling of its
thickness will produce a clearly noticeable reduction of the sound
coming through it.  Even better would be to put some furring strips to
create a cavity between the layers and put fiberglass in the cavity.  Is
the skylight plastic or glass?  If it is lightweight plastic, can you
cover it with something or install another layer of plastic with a space
of at least 4 inches between layers?

Good luck

Noral Stewart

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