You can tell him guests need to be out of the house by 10 pm.

Otherwise, it can be done but it is invasive.

www.tmsoundproofing.com/wordpress/?page_id=107

You can blow foam insulation into the wall cavity, without having to rip out the drywall. Or you can rip out the drywall on one side of the wall and again put Bat, or Blown insulation in. These are the two things I suggest pricing out with an Insulation company. Drywall is very cheap and painting one side of a wall is not expensive either.

As noted by National Research Council of Canada building scientists:

"Sound-absorbing materials are only effective when used in assemblies with the faces correctly isolated [via resilient channels, double-stud walls etc]. Using sound-absorbing materials in a rigidly connected assembly is a waste of money."*

Even when properly isolated, much sound will come through "flanking" routes, i.e., the floor and ceiling, so you may experience little perceptible reduction.

As worthy pointed out, insulation beyond just inside the wall is important. However I would still recommend resilient channels and another layer of drywall despite what was noted. Take a look at your ducts to see if alot of sound transmission is traveling through those as well.

This Quiet Rock, would quite possible help as well.

One cheap way to help reduce sound transmission is by using 2x6 framing with staggered 2x4 studs. That way, no stud is connected to both drywall surfaces. Fill it with rockwool.

Sure, there are still doors, floors, and ceilings, but for those looks to just reduce noise rather than soundproof, this is an inexpensive solution.

I've used Quiet Rock and resilient channels with mixed results at best in both new construction and renos. Green Glue is another version of the same approach that has its fans too.

Worthy is correct about flanking sound. Unless the space above the wall is closed (with drywall not insulation) adding drywall to the wall will do little. Investigate these paths first. If there is a door in a wall there is little you can do unless you use a solid core door with an acoustic perimeter and a drop seal at the floor. Check to be sure the undercut is not needed for air return.

Silence is impossible for a shared wall and might not be the most important goal.

This potentially may fall under the "Social Behavior" forum.

Sound travels in various ways: 1) airborne; 2) impact; 3) vibration. There are at least three strategies for effective acoustical control: 1) mass--create enough mass to stop the airborne acoustics; 2) decoupling--introduce an air space between the source and the desired acoustical space to mitigate the impact sound; 3) dampening--eliminating or mitigating vibration at the source. One solution, without the others, is a third of a solution!

Hang inexpensive area rugs on the selected wall, ceiling to floor.

The last time I installed "soundproofing" between rooms at a client's request, she specified "a bit quieter but I still want them to hear me when I'm shouting for them." Quiet Rock met that demanding standard.

I assume it is the wall between the two bedrooms that concerns you. If sharing a bedroom wall is unavoidable and you have found a way to close flanking sound paths (above, below and through ducts and outlets) adding insulation or a second air cavity would be helpful but according to acoustic tests neither would be as effective as adding a layer of resilient gypsum wall board (GWB) to one side. The usual options for this are: GWB adhered with Green Glue; a layer of QuietRock or GWB mounted on resilient channels or a proprietary acoustic channel system. This is in the order of increasing effectiveness and cost.

The principle involved is that for a wall of limited thickness, sound energy is dissipated more by resilient materials and systems than by insulation, air or thin rigid materials. These systems are in the "let it shake" school of "decoupling".

But first, visit the house and test the sound transfer. If it is a well built house, it should already have some kind of sound treatment for the shared wall even if it's only insulation.

For more info visit the "products by use" section of Isostore.com

Wait until you are in the house and see what it's like. Sometimes just hanging a rug on the correct wall stops bouncing sounds.

We used that "Green Glue" between office and a bathroom, with an addistional layer of drywall - it made a huge difference in through the wall transmission.

VENTS! They transmit noise very effectively, just like an old-fashioned speaking tube. One way to minimize transmission is to install some sound deadening foam inside the ducts so you can't bounce noise between rooms.

The cheapest sound reduction on a build is a better design than backing up two bedrooms to each other.

lazy_gardens, please describe in more detail what you meant by install some sound deadening foam inside the ducts so you can't bounce noise between rooms. How effective would a vent be if it was plugged with foam? I must have misunderstood you.

Thanks for the suggestion on double drywall/green glue. That could work for minimal loss of space.

Carol

All of these techniques are explained in great detail at isostore.com

It may not be feasible to add acoustic lining to existing ducts and the dicts might not communicate between bedrooms.

describe in more detail what you meant by install some sound deadening
foam inside the ducts so you can't bounce noise between rooms.

Wrapping or lining the ducts can reduce transmission of some sounds. Sometimes, just the sound of the air rushing into a room drives some people batty. (If they're not already.) But as far as residential soundproofing, this is really getting into esoterica.

Thanks JDS and Worthy for the info.

Carol

If I am building new construction and want soundproofing between floors, as in first, second and basement, what would be my best option?

First, attach the drywall ceiling on metal resilient channels and avoid ceiling penetrations. Then consider floor cavity insulation, softer floor finishes and flooring underlayment.

Its all explained at the iso store

Besides all the techniques noted in the above thread, there are a number of speciality products for floors and particularly intersecting building planes, i.e., walls, floors, ceilings. (Co. link is for illustration only.)

As leading researchers have noted, flanking pathways defeat the best laid plans. In one home I built, the heating ducts were like a speaker phone between the kid's basement play room and a second-floor bedroom. Separate HVAC systems by floor was a design that would have cured that.

A designer friend gave me a tour of a Swiss bank headquarters under construction in a downtown high rise. The board room was entirely lead-lined.

If you're prepared to spend serious money on sound-deadening, consider hiring an acoustical consultant.

Sorry, it was for sound attenuation, a very common use. Besides, lead is not the preferred metal for Farraday Cages, which aren't evidently all that effective anyway for blocking sending devices.

I've used lead to absorb the longitudinal mechanical waves of airborne sound in recording studios and lead blocks the transverse waves at the short (Xray) end of the electromagnetic spectrum, but to block the long (radio) waves at the other end of the spectrum, metals with a high level of electrical conductivity are used to absorb and disrupt the waves. Copper has 12 times the electrical conductivity of lead and its also magnetic.

So, lead might reduce the strength of radio waves but not block them entirely. Instead, grounded copper and aluminum foils or screens like the Faraday cage Worthy mentioned are used.

But I worked for an architect in Geneva and they were still using T-squares.

There's not many good options in an existing build, unless if $$$

Besides the obvious placing closets/bathrooms/etc between bedrooms and public rooms, here is my personal opinion for best bang for your buck (in a new build):

1. HVAC is the worst culprit. Duct Liner product inside the ducting.

2. Standard batt insulation in walls. Very cheap, gets rid of most of the hollow echo sound

3. Opt for that "quiet rock" stuff or whatever brand of "soundproof" sheet rock you find

4. $$ Floating framing

I've seen all sort of double-rocked walls with air between, tons of spray foam... There's a lot of diminishing return especially with limited space. Or do what hotels do - concrete floors and walls ;)

Lined ducts make Dr. Lstiburek's list of top 10 dumb things to do when building a home in the south. And with the humid summers in many so-called cold climates, probably not a great idea there either.

concrete floors and walls

As long as they're carpeted and the walls are finished with resilient surfaces.

There are many impartial sound rating assembly comparisons on line, such as this one from the US Department of Housing and Urban Development.

Stuffing in a bit of fibreglass, the favourite "soundproofing" solution of so many builders who disdain all this on-line chattering, is not very effective, at the most raising the STC rating by 3.

^ I wasn't thinking humid south... But wouldn't only dried AC air or hot furnace air be going through it anyway? I have zero experience with southern humid air.

Try having a party in a room, going to your bedroom, and tell me where most of the noise is coming from though ;) Like kids talking through cardboard wrapping paper cores

In the summer we have two dehumidifiers running constantly in the basement to try and keep the rh below 50% in our "cold" climate. I can only imagine the condensation within the ducts. Commonly used fibreglass duct lining can't be cleaned and when disturbed can create a common source of dusty mould.

Roxul makes a great insulation product called Safe and Sound http://www.roxul.com/products/residential/products/roxul+safe'n'sound

Some good videos about it on youtube too.

Roxul is great, it's just mineral wool. There are other brands such as Fibrex, Thermafiber, etc that make the same stuff. Mineral wool is superior for sound control and firestopping... but when comparing to fiberglass batts, we are still talking about installing them in a rigid wall so how much better it would be I couldn't tell ya.

Don't let the soft green fuzziness fool you, it's just as itchy as yellow fiberglass lol