Sound Insulation

[shake777]

Gilbert, You are at least partially right at worst. The only issue is that noise comes through our forced hot air vents directly over the mains, width, center, and subs. The sound is leaking into the master br and bath. Although my wife doesn't seem to be bothered by it, it bothers me and I'd like it to be quieter if possible. I thought maybe someone had run into this and found some sort of magic material to stuff into the vents that would keep the sound from traveling though and still let the hot air pass. It seems relatively impossible to me but I thought why not take a shot in the forum why you all have never really failed me yet. I imagine it will be better after we put some more insulation on the ceiling, drywall, and put a floor with wall to wall carpeting.

My question is really focused on the forced air vents. Is there any way to keep sound from coming through them? I wish I would have titled this thread differently to make it more clear about what I'm after. We never get any complaints from the neighbors and I have even been over there while my system was cranked up a little and you can't hear anything. Thanks Nic

[shake777]

Heres a pic that shows the configuration of the speakers. I guess the vents in the br and master bath are directly over the screen or close to it although I have never seen them because of the insulation under the ceiling. I can see the vents up on the main floor and hear the sound leaking through.

The heating/ac guy is coming in a day or so anyway so no biggie if you don't have an answer. I posted this before we made that appointment. I sure appreciate all the great responses I've gotten about this issue including yours. Nic

[shake777]

As an afterthought the unit next to us and the firewall are on the left wall. Fortunately the front and right walls are adjacent to the outside as we are an end unit. Thanks again all, Nic

[pite]

Its amazing to get that kind of reduction. I'm waiting for a quote on the accoustiblok materials. However, as noted above, my best hope is in the firewall. I took a visit to my neighbors yesterday with my system turned up a little. You could have knocked me over with a feather as there was no, none, zip, noise from my place. That's with the subs at moderate volume. I'm totally relieved although I do plan on spending a goodly amount so I can crank it up when I want. Thanks again for the help. Nic

That's a relief! I'm curious and interested in what you ended up with this finally...Thanks!

[Greg Oshiro]

There are many excellent suggestions in this thread. The problem is deciding how much of which solutions to apply *to your particular circumstance*. You need an acoustical consultant. Call a local university with a good engineering department. Acoustical folk can generally be found in Physics, Electrical Engineering or Mechanical Engineering. They should be able to recommend someone local to you. Let us know how things go.

[shake777]

Greg, Thank you for your response. It so happens that there is an excellent University just minutes form my home and I almost surely will inquire there when the time comes. We are still stuck not knowing if the repairs done to our basement are going to hold up to the cold and snow so we will wait it out this winter. Hopefully springtime will be go time. Its worked out well because the picture shown is obviously not the system iisted in my signature. Kind of lucked out on that as it came in very inexpensively and my wife gets a nice Christmas present for her role in seeing to it that I'm happy. Even with all the cement and open area its a phenominal experience I look forward to every day. That's given the great systems I've seen in the forums which would put me to shame which I will never be able to match. That's fine. I'm way past my original expectations and after following your advice who knows what will result? My heating guy told me there's no way to keep sound from leaking through the vents. I'm hoping against hope that he's wrong. Nic

[Greg Oshiro]

<snip> My heating guy told me there's no way to keep sound from leaking through the vents. I'm hoping against hope that he's wrong. Nic

Hoping not required:

http://www.industrialacoustics.com/usa/commercial/index.asp

These are not usually found in residential HVAC systems. I haven't looked through IAC's offerings to se what they have that might work. That's what your acoustical consultant will do...

If you want to read up on acoustical noise control:

http://www.alibris.com/booksearch?qisbn=9780070268142&matches=14&ework=2794679&cm_sp=works*listing*title

Maybe you can DIY it...

[garyrc]

You are getting some great advice! Share all your sources with your contractor, and s/he may learn something, too. Mine did.

• In building up your wall layers (e.g. double sheetrock, or sheetrock over sound deadening board, or sheetrock over 3/4" plywood) be sure your contractor staggers the seams, uses code approved glue between any touching layers, so they won't vibrate or buckle against one another.
• You can have two independent floor plates, each with its own studs, with an air space between the plates themselves. Same with ceiling plates. This is shown on page 80 of Jeff Cooper's Building a Recording Studio his designs are for home studios. He recommends 1/2" sponge rubber underneath the floor plates. Check local fire codes.
• Electrical outlets that are not being used should be sealed so they won't leak sound.
• If you are on good terms with the people on the other side of the wall, let them know what legnths you are going to; that may increase their tolerance for the occasional sound leak. Some people negotiate "no loud sound after midnight" or something.
• One of the most soundproof walls is made out of common concrete blocks (sometimes called "cinder blocks") filles with mortar or sand with single or double 5/8 sheetrock with a resilient channel holding the sheetrock to the blocks on either side of the blocks. This is shown on page 83 of Cooper's book. The STC can be as high as 65-70 compared to 30 to 35 for an ordinary interior wall. The common concrete block walls have to be on something strong enough to hold the weight. It looks like you have a concrete floor, right?
• Make sure everything is braced and supported or wedged, in case of earthhquake. Even though it's nothing like the West Coast, New York will have one sooner or later.

[Arkytype]

While the tried-and-somewhat true "mass law" sound isolation techniques can be utilized, you might want to consider a more effective, possibly less expensive approach to keeping your neighbors happy.

Hanging drywall (walls and ceiling) using the Kinetics Noise Control IsoMax Sound Isolation Clips http://www.kineticsnoise.com/arch/isomax/index.aspx results in a higher Sound Transmission Class (STC) rating than multiple layers of drywall and staggered studs. Read the Construction Analyses links to see documented performance comparisons. The clips run about $6.00 each and they attach to traditional steel furring channel which any drywall supplier has.

I used their RIM Concrete Floating Floor System http://www.kineticsnoise.com/arch/rim/concrete.aspx to isolate a high traffic space above a university TV studio a few years ago and the staff has never heard any impact noise from above the studio. As the studio was located 25 feet! from a state highway, other CK products were used to create a 15-inch thick outer wall sandwich composed of isolated brick wall+airspace+concrete. The measured noise level in the studio with the muffled air handling system operating was an impressive NC17!

Lee