You don’t hear (pun intended) much about residential acoustics unless you are talking about houses in airport flight paths or along busy highways. However, during a recent interview for the Chicago Tribune, I starting thinking about sharing what we know about sound issues in residences. Even if you don’t have offensive noise generation outside of your house, it is entirely possible you may have some inside—especially if you have teens like I am about to.
Here is a link to the article
Indoor noise issues (sounds you don’t want to hear) come either from ‘in the room’ sources (say a TV that is too loud in an echo-rich environment or a husband who snores) or ‘out of the room’ sources (say my son playing his favorite Black Eyed Peas songs at full volume, or the AC unit).
The ‘in the room’ problems generally are due to reverberation (echoes) in the room. If the room has a lot of hard surfaces (especially if it is big), sounds in the room reflect off the various surfaces and create a lot of extra noise. This is a big topic for a later blog post, but suffice it to say the most common solution is to add ‘soft’ material such as curtains, furniture, rugs, people, etc. to help absorb the sound so there is less reflection. The other solution is of course to reduce the level of sound in the room (not so easy if it is a snoring husband -- although CPAPs do help for this source).
‘Out of the room’ problems are more difficult. Sound is pretty sneaky in that it can move through air and it can move through solids. Here are four tips for solving noise issues in your home (or church, office, or whatever).
The best and cheapest method of dealing with noise transference from one room to another is planning. We laid out our house so that the media/family room was above the garage and only shared a wall with one other room, so that the master bedroom had no rooms above it (and the AC units that are above it hang from the roof structure), and my office is set in a quiet place between the master closet and entry. All of this reduces potential noise flow. Conversely, we purposely had the kids’ bedrooms open to the great room, so that we can hear what they are doing (perhaps a mistake as they turn into teens, but we really didn’t want to be too separated from them). One other thing to think about is where noisy elements like AC units and pool equipment are in relation to your rooms and windows.
Here is a Plan Diagram of the Second Floor
2. Wall Design
You will never be able to completely design away all possible noise issues. Next you need to look at how your walls are designed. Remember that not all walls have to be built the same—save your money and focus on the most critical areas when using more costly techniques. The first thing with noise transmission is wall mass. Adding masonry (exterior) or insulation helps reduce noise transference. We used Quietrock, which is a noise absorbing drywall, and it has worked great on the wall between the kids’ rooms and the wall between my wife’s office and the media room. Double walls and resilient channels also help reduce the noise transmission.
3. Air Gaps
Sound is sneaky. You can have a exceptionally good acoustic wall, but if there is one small hole in it, the sound can get through and your ears will adjust to the sound. That being said, you need to make sure there are no holes in your walls. If it is an exterior wall, pay close attention to sealing the windows and any other penetrations tightly (you should be doing this anyway). Watch for back-to-back plugs and switches as they can create easy sound paths (really you should separate each box by at least one stud). Using acoustical sealant at the tops and bottoms also helps.
4. Flanking Paths
Before WWII, the French built an impenetrable network of defenses, called the Maginot Line, along the border with Germany. The problem is that Germany invaded through Belgium and outflanked the defense.
Don’t let this happen to your acoustic wall. Ceiling elements, especially recessed cans, can allow sound to get into the attic and get around the walls. Similarly, AC ducts can allow sound to move from room to room. If you really want a room to be separated, look at insulating the ceiling and floor. You can even have a separate AC system for a room like a media room to prevent it from putting sound into the ducts. Lining the ducts or putting sound baffles in the ducts can also help.
There are lots of things that can be done to reduce noise transfer from one room to another, but if you follow these four tips, you’ll be way ahead of the game. Designating problem noise sources and which rooms need to be isolated from this noise early in your plan will go a long way toward avoiding ‘noisy building syndrome’. Be sure to discuss this with your professionals early in the design process, though – an ounce of prevention is worth a pound of cure!
Here is a Plan Diagram of the First Floor