Stopping noise travelling through cooker extractor

[VerticalTobe]

Hope this is in the right section - it didn't seem to fit anywhere else.

Wondered if anyone had any thoughts or ideas on a (simple?) way of stopping noise being transferred through our cooker hood - for some reason from the outside you can hear conversations going on inside, and when you're inside you can hear next doors annoying yapping dog like it's standing right next to you*

The ducting is the rigid square type -there's only around two and half meters from the hood to the outside with only one bend in it. The outside has a gravity flap fitted which closes tight (with a magnet to stop it flapping in the wind) when not the fan is not on.

* please note, getting rid of next doors dog is NOT an option!

 

[big-all]

do you have a filter in the hood ??

 

[VerticalTobe]

The filters are the metal grid types that say they don't require anything additional - don't know if the paper style filters would be thick enough to filter out noise.

 

[AronSearle]

Not sure what you can practically do.

Soft materials such as filters will absorb sound, but as you say I wouldn't think they would make a huge impact.

Lining the pipe with a soft material, and increasing the number of bends would reducing the sound funnel effect, not sure how practical such advice actually is.

Maybe putting a plywood box over the vent could help, with enough holes to let air escape (on the sides and bottom), this would reduce sound directly hitting the vent outlet and transmitting through the pipe.

 

[foxhole]

You could try a wind baffle, adds another obstacle for the sound.

http://www.vent-axia.com/range/wind-baffles.html

 

[VerticalTobe]

I've considered lining the inside of a part of the vent that's easy to disconnect and get at - there's a straight run of a meter which can just be uncoupled. The only issue is what might be best to line it with; something like a class O type fire retardant might do it?

Then a bit of Googling eventually located this

http://www.polypipe.com/ventilation/news-article?id=4f05a9c93dd23a9d52000000

which seems like it might work without having to go to the hassle of finding a suitable material to use myself (and avoid the problem of adhering it correctly the the ducting). The downside is the price - almost £100 for a meter run!

And the big question in my mind is, will the thing actually work if I shell out that amount of money? If it doesn't I'd be seriously upset.

 

[big-all]

buy a bit off this and just lay it in nowt to loose
http://www.toolstation.com/shop/p39632

 

[VerticalTobe]

With that and the price of the foam it comes to just under £50 - seems worth a stab

 

[big-all]

try it on its own nowt to loose

 

[wobs]

Add a bend or two in the ducting. This will stop a suprising amount of noise travelling down the duct.

Lining it with something soft will reduce noise a bit, and certainly stop the noise escaping through the side of the ducting, but a bend would be more effective if the noise is escaping through the opening at the end.