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Need help with soundproofing

umbach's picture

I'm finishing my basement and creating a theater, entertainment area. Problem is, the cold air return from the master bedroom connects directly to the main trunk running the length of the basement. That trunk picks up the sound  in the basement and transmits it into the master bedroom like you're talking on an intercom.   The basement ceiling will be dropped tile. What can I apply to the cold return duct to significantly reduce the sound transmitted to the master suite?

umbach (post #207431, reply #1 of 7)

uneducated guess-

Isolate the duct (cushion it/vibration reduction) from the joists.  Add rockwool or some type of sound deadener immediately outside the duct.   Then add mass to a surround-couple layers of drywall-sandwich of homasote/drywall.  Might add a noise dampener in between sections of duct-rubber flex connector.

Use the most acoustic tile you can with deep grooves, heavy texture.............hunt down the best.

Along the walls, add some sound absorbers to catch soundwaves b/4 they start to transmit the vibrations to the side walls.

Wear ear muffs in the bedroom, add hearing aids or headphones (optional) to the basement.


Think of all the years someone in the basement has been listening to the antics in the bedroom.

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Remodeling Contractor just outside the Glass City.


Scrap linoleum, glued to the (post #207431, reply #2 of 7)

Scrap linoleum, glued to the outside, will keep the metal from vibrating, and hence prevent transmission of sound through the duct wall and into the duct.  But you still would have trouble with sound that enters through a register, if you think that's a significanty part of the problem.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

That trunk picks up the sound (post #207431, reply #3 of 7)

That trunk picks up the sound in the basement and transmits it into the master bedroom like you're talking on an intercom


pre telephone those were called 'speaking tubes'  <g>

think you are stuck with re-routing ductwork and eliminating the direct duct, plus adding baffles

There's probably not enough (post #207431, reply #4 of 7)

There's probably not enough room but if you can put offsets in the return air to look kind of like a straight Z.  Add lined duct and insulate the outside.  Add batt insulation on top of the ceiling tiles.  You could drywall around just the main trunk duct in the basement.  Frame around, insulate add 2 or 3 layers of 5/8" sheetrock.  You could use a product like Quietrock or Supress board, instead of or along with the 5/8" to deaden the sound.  Hope these ideas help.

Try egg cartons,  believe it (post #207431, reply #5 of 7)

Try egg cartons,  believe it or not its a good sound deadener. 

When you plan to begin a remodeling project, it's best to do your research so you will have the best results without going broke.

Dynamat. (post #207431, reply #6 of 7)

Look into DynaMat and its cousins on Amazon. Used by car stereo people to stop steel from vibrating / resonating.

Vastly more effective than the other materials suggested. Those materials could be used after dynamat to further attenuate sound transmission, if needed.

Also, seal the ducts (which ought to be done anyway) to stop sound from getting into them.


Good luck.

Use the Scrap linoleum to (post #207431, reply #7 of 7)

Use the Scrap linoleum to stop the metal for vibration because it will reduce the transmiision of sound and also try to seal the ducts and you can also use the sound proof sheets but also consult with any expert.


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