Soundproofing a basement bedroom

[gerry gardiner]

We have a 28 year old bi-level. The living room has finished oak floors and an area rug. My son is has the area below this for a bedroom. That area had been a rec room for the previous owners and the ceiling is already finished. There is an air vent common to both the rooms. Any recommendations in deadening my sounds from upstairs? Sealing of the vent, top and bottom, is OK as the upstairs is wide open to the rest of the house and a separate heater is used, when needed, downstairs. TIA, Gerry

[Joseph Meehan]

I assume that is a air return vent?? Unless it is not connected to any heating, cooling or air return for heating or cooling devices you do not want to just block it off. You can greatly reduce the function of the system and maybe damage it.

Air to air transfer (your vent) is likely the biggest problem. There are some ways of addressing it, but they depend on the specifics of construction.

For a lot of good information, and a possible source for some materials, take a look at:

In general you want to block air exchange. Air caries sound very well. (Try opening your car's window as a train is going by.)

Next you want weight. Heavy things (drywall lead sheets etc.) block sound well.

You also want to prevent any direct solid connections. Stagger wall studs or use special isolation devices to keep the sound from traveling through the wall (remember the two cans on a string (well wire actuarially worked) you want to break the wire).

Filling in wall cavities with sound absorbing materials (accustical fiberglass bats) will do a little.

Point source control (special absorption material) at the source of the sound will also help.