[[email protected]]

Problem:
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.

Considerations:
-- 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
long-term problem.


Proposal:
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-
flow.


Questions:
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
consider?


Thanks!!!

[Richard Crowley]

wrote ...
Proposal:
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-
flow.

I would start by just trying a ~18-24 inch square of
"finger foam" (the kind with an array of "fingers"
cut into one side. Have someone hold it around the
vent to see if it has sufficient acoustic dampening
effect to be worthwhile.

NOTE: Most anything you put there that will truly be
good at absorbing sound will almost certainly also be
very good at collecting airborne lint also. This can
easily build up to become a fire hazard unless checked
and cleaned out VERY frequently (monthly, at least).

[[email protected]]

I would start by just trying a ~18-24 inch square of
"finger foam" (the kind with an array of "fingers"
cut into one side. Have someone hold it around the
vent to see if it has sufficient acoustic dampening
effect to be worthwhile.

NOTE: Most anything you put there that will truly be
good at absorbing sound will almost certainly also be
very good at collecting airborne lint also. This can
easily build up to become a fire hazard unless checked
and cleaned out VERY frequently (monthly, at least).


Agreed. I'm definitely aware/concerned of creating a ventilation
issue and the lint-collection problems associated with it. I'm hoping
I can do this without compromising on safety, of course. Thanks for
the comment, though. Much appreciated!

[Ed Anson]

wrote:
Problem:
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.

There are two other possibilities you ought to check:

1. The noise might be propagating through the wall. Depending on
construction, some walls are quite capable of transmitting sound. If
that turns out to be the case, just a bit of foam or something where the
vent passes through the wall might fix the problem.

2. If something is indeed resonating, changing its size (and thus its
resonant frequency) might help.

[[email protected]]

There are two other possibilities you ought to check:

1. The noise might be propagating through the wall. Depending on
construction, some walls are quite capable of transmitting sound. If
that turns out to be the case, just a bit of foam or something where the
vent passes through the wall might fix the problem.

2. If something is indeed resonating, changing its size (and thus its
resonant frequency) might help.

Yes, that's definitely something I've thought of. Maybe as a multi-
pronged approach. Wouldn't be too difficult to enlarge the existing
hole/vent pipe. Thanks for the comment!

[Arny Krueger]

wrote in message
oups.com
Problem:
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.

Is this a mechanical or acoustical resonance?

Usually, the normal collection of bends that one gets in a dryer vent
system, and the normal outdoor vent, tends to attenuate much high frequency
mechanical noise that might be coming out of the dryer itself.

There is tip number one - maybe your venting system doesn't have enough
bends to attenuate the noise.

If you replace flixible dryer hose with like diameter PVC pipe, then there
is a much stronger damping effect, and more containment of noise and
vibration.

Since the interior of PVC pipe is a lot smoother than normal dryer hose,
there are far fewer problems with lint hanging up internally.

PVC pipe is pretty cheap and easy to work with. It's the fittings that may
sting the pocketbook, if anything.

I connected my PVC pipe venting system to the dryer with a short length of
flexible vent tube and a couple of stainless steel hose clamps. It's vastly
overbuilt but it looks and works great. It has already outlasted one dryer.

[Scott Dorsey]

wrote:
Problem:
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.

So, it's mostly high frequency stuff, coming out of the vent. Put a
90' corner section on the vent outside the house, and direct the vapour
and the sound in another directionl.

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- flow.

An automotive-muffler type cancellation box might be possible as well,
although that's more effective at lower frequencies. But I'd try
redirecting the flow before doing anything else. If the problem is
that the noise is all going in one direction and is effectively being
concentrated, make it go in another less harmful direction.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Ty Ford]

On Sat, 30 Jun 2007 22:30:39 -0400, wrote
(in article .com):

Problem:
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.


Have you been in their space to hear the sound they are objecting to?

Regards,

Ty Ford



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