sound transfer through return air in door grill

[michael1123]

I have built a sound proof wall, the wall works great. the solid core door has a 12 X 12 grill in it for return air, I need to make the door sound resilent without losing any substantial amount of air.Is there any type of sound baffle that will go in to a 12X12 grill.

 

[Tmoose]

What is the grill letting out that must get in somewhere else?
I lined the ducts (formed by the floor joists)leading to the return air grills with several inches of regular old fiberglass insulation, with a chamber a foot or so deep at the end. I think you need a long, line path from your grill.

http://www.soundservice.co.uk/Simple_Baffle.gif

 

[Rob45]

Tmoose is right: you aren't going to be able to get any significant amount of sound transmission loss in a "duct" 12" x 12" x 2" long.
The door needs to be solid, and you get your air someplace else.

 

[GregLocock]

Designing the air handling gear in an engine noise test cell (for example) is actually the biggest part of the job after the floor.

you need to say what frequency you need to attenuate and by how much, and what air flow rate you need through the grill. As Rob says, it s probably impossible.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[KiwiMace]

On soundproofed VIP offices, my method is to duct the RA through the partition and someways into the main floor plenum to discharge. This duct is lined and sometimes builtup with a layer of gypsum board. Door grilles are for tearooms, bathrooms and other rooms of equal importance.

 

[amorrison]

Check out a ASHRAE Handbook - Systems volume.

- the Sound and Vibration Control chapter.

See your friendly HVAC engineer or an engineering library.

The answer will probably be a lined elbow and ductwork attached to the door.