Noise abatement problemto be solved
I have a customer who has 2 vents, one on the second story trim board, one at waist level near the ground. Both emit too much noise.
I built a box for the top from plywood, 5′ long and enclosed on the top, front & bottom, and left open on the left & right sides. The inside is lined with mineral wool insulation. It is nailed on to the trim.
The readings show us we are 1 db too loud.
The bottom one is also 5′ long, but 14.5″ top to bottom, baffled on the sides with only a small side exit on each side, and the bottom is not muffled so the hot air can be vented. On that one we are 8 db over.
The environment is hard. Two tall (2½ story) houses 8′ away from each other; a 6′ cedar fence and gravel (soon to be paving stones) on the ground. Any suggestions?
I’m going to try & import the pictures into this post with Infranview, which I’ve never used.
Quality repairs for your home.
AaronR Construction
Vancouver, Canada
Replies
Sorry folks, let's try it out of Photoshop.
Quality repairs for your home.
AaronR Construction
Vancouver, Canada
What sound are the vents emitting? Its pertinent to the construction of what you'e building.If you think of a auto's muffler you might do better. They're constructed so as to reflect the exhaust impulses back into the incoming exhaust stream so as to break up the sound impulses.
Think air conditioning/heat recovery vents.
I'm going to put baffles on the sides of the top unit, and enlarge the lower unit downwards, putting in another baffle.Quality repairs for your home.
AaronR ConstructionVancouver, Canada
Hmmm, Vancouver, Air recovery... Do you have the odor control taken care of as well?Just Kidding. :)I think that building one or more baffles covered in insulation should take care of the lower one, and one baffle should surely take care of the top one that's only 1 db over.
Lots of noise level requirements to be met these days.
a 1db difference is if I recollect right, the change in sound intensity just barely perceptible to the human ear, but I could be wrong. Anyway, it ain't much in the sound spectrum of things.
I can walk out my front door here in Calgary and ambient road noise can exceed the allowable maximum noise level for our bylaws, for which I have no recourse.
I betcha that somewhere in the bylaws yer trying to conform to, there is mention of ambient noise, which could rationally get subtracted from your noise meter readings. But who's to say rationality is in play in your situation.
Of course you know that there are different wieghtings for sound levels- A B and C- maybe more these days -As I recall from reading "the tyranny of sound" years ago, these have to do with the frequency of the sounds.
And you might want to look at where you are required to measure the noise. At source? or a the point a person would hear it. Like , for example, inside the adjacent house....
You might want to look at "time requirements" for offending noises, and maybe put a timer on the vents to cycle on and off every 15 minutes, or whatever time frame an "offending" noise is permitted to
occur.
Can the ducting be wrapped with duct tape or perhaps some engineered sound dampening tape
http://www.soundprooffoam.com/pipe-soundproofing.html
Or what about flexible connections that do not carry vibrations along the length of the ducting.
I'd love to know more about the story....and the solution.
Eric in Calgary
I'm cheap and only have dial up access to net...I could walk over to your cabin and back and still do that quicker than I can download those photos. Sorry!
Sorry about the impending hijack but since this thread is about noise abatement...
What is the best product out there to dampen sound on interior walls?
blue
March JLC had an article Innovations in Sound Control that covered this issue in depth. Apparently there are loaded vinyl sheets that are quite effective in some situations. Overall there are many details that can't be overlooked for good sound control. Apparently elaborate home theaters are driving some of the acoustic engineering in residential construction.
You have to watch these Home Theater articles. A lot of them are oriented toward control of reflected sounds within the listening space (a real problem in current Home Theater environment). But they are unrelated to sound thru the walls.
still no solution to yer problem?
Eric
Tell 'ya what I did.
I put a bottom on the lower vent and surrounded the area with Roxol.
Then, I put baffles on the edges, so that the vent only has about 18 sq in to get out on each side; plenty, for the application.
On the upper one, we stuffed it 3/4" backer foam inside any area which was slightly open to the atmosphere.
We're waiting for the sound police.Quality repairs for your home.
AaronR ConstructionVancouver, Canada