Our house in the city shares a common wall with our neighbor. At the
back of the house, our dryer vent is positioned about 8 feet from this
common wall. Nothing is wrong with the dryer according to a repair-
person and anyone's casual observation. The vent pipe is not
obstructed at any point. The exhaust vent fan (or dryer blower?) does
make a typical "whirring" noise which escapes from the vent and
resonates in a way which disturbs the neighbor. As crazy as it seems,
I now believe it's a legitimate problem for them due to the
configuration of the buildings and back yard.
-- I could possibly re-route and add to length of vent (limited by
dryer spec, of course), but would prefer not to. Besides, I'm not
sure it would help much by itself.
-- This is actually a dispute between our tenant and our neighbor, so
I'd like to keep them both as happy as possible. It's also been a
My idea is to build a "sound-absorbing" box (approx 2' x 2') which
simply attaches to the building, over the existing dryer vent. I
don't want to restrict air-flow in any way, so the box would have to
have to have an appropriate opening for the air to escape. I'm
envisioning a simple box [a] lined with some sort of thick, sound-
absorbing foam, [b] having a hinged door to allow any cleaning/lint
removal, and [c] having a sufficient design to allow for adequate air-
1. I know acoustics is a complex area. However, could something like
this actually mitigate the "whirring" sound of a clothes dryer as it
exits at the vent?
2. I've researched acoustic foams on the web. Any thoughts on what
types might work best for this application?
3. Would the placement of the air-flow exit hole(s) within the box
impact the efficiency of any foam?
4. Any other design elements (or other suggestions) which I should
On Sat, 30 Jun 2007 10:05:04 -0700, email@example.com
I don't think so either.
I think any box, even without a lining woudl do a lot if it stood in
between the noise and the people listenign. But a lining would be
good too. Any lining would be good, an old shirt, an old flannel
shirt, part of an old blanket. That's assuming the open end points
down and it won't get wet.
I think you can just omit one side of the box, a side that doesn't
point to any people, and that will make cleaning easy, and assembly
There must be an acoustics newsgroup (or a music one) or yahoo list,
or even a web list of some sort.
You shoudl be able to pin down all the places where the noise is
coming from by using an automotive stethoscope, which JCWhitney and
maybe Harbor Freight has sold very cheaply, under 5 dollars. But if
you don't have one of those, you can use a stick. Even a wood ruler
or a yard stick. Two feet is a convenient length. Touch it to the
various spots and hold it near your ear, and you'll hear things that
only owls and leopards could hear without the stick.
Narrow down whether it is the air coming out of the pipe that has the
noise (You need something else to hear the air**, but if nothing else
is making noise, it's the air, I think.) or the end of the pipe, or
the louvers there or whatever.
I don't think you need best. Any foam, including the left over
peed-on mattress from the crib, will do 75% of what the best foam will
do. Anything that's not hard, whether foam or not, will do 60%.
These are just my guesses.
Yeah, I'm not certain to what degree the pipe amplifies the noise
originating from the dryer. I've taken the pipe off the dryer, and I
can hear the same "frequency" (coming from a non-expert). But,
perhaps the pipe is actually amplifying it. Currently, the pipe
(flexible aluminum) is only about 6' in length from the vent fixture
(which is a simple hood/flap).
Then wouldn't there be even easier things, like tying a belt or
blanket around a part of it? (I'm assuming it gets nowhere near hot
enough to set fire to a blanket, or you could use leather or tie a
piece of wood or steel to it.) Or tying a rope around part of it and
tying the other end to some place fixed. The rope around the pipe
shouldn't be at the middle, or at an even third, quarter, fifth, etc,
but somewhere that would interfered with the frequency one is hearing.
I guess just tie it up and move it a quarter inch at a time.
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