|  THE
BASICS:
When solving a noise problem, you need to
establish a few things: 1) Is the noise coming from within this space
or is it coming from an adjacent space? 2) How loud is the noise in dBa
(Decibels) Radio Shack sells a sound level meter for about $60, its not a very
good one but it will put you in the ball park. 3) How loud would you like
it to be. Keep in mind that most homes and office spaces are at or about 35 to
45 dBa to begin with. Dead Silence is not a reasonable goal. Now
for some answers: If your noise source is in another room and you'd like
to keep it there, you need to increase the transmission loss (TL) of the materials
that make up the partitions between the rooms (i.e.,drywall, plaster, doors, windows).
Products that increase the TL of a partition are rated with an STC (sound transmission
class). Be very careful when looking for "Sound Proofing" products that
do not give you an STC rating if you want them for increasing your TL. Some products
will be rated with an NRC rating. The NRC rating is something completely different
and is part of the most commonly misunderstood functions of acoustics. Sound Proof
Foams are also usually a misrepresentation. In order to increase the TL of a partition,
you must increase it's mass. Closed cell foam and spray on material don't do this.
That's not to say that they don't have their place in acoustics. They just don't
work for this problem. Look for products that have an STC rating of STC 26 or
higher. Some of these may be a loaded vinyl barrier that weighs 1 or 2 pounds
per square foot. Another great material is good old fashioned drywall. Adding
an extra layer of drywall to an existing wall (as long as there are no holes in
it) can make a dramatic improvement. You can kick it up a notch by mounting the
drywall on isolation clips (try to stay away from resilient channel, it's to easy
to short circuit). Another thing to remember when buying soundproofing materials
on the Internet is that you're dealing with a company that could be anywhere.
Make certain that their website shows you who they are, where they are, and how
to contact them via other means than e-mail. You should be able to call and speak
to someone if you have questions. Soundproofing Stuff isn't cheap - don't be afraid
to get help. Matt Oeler
President
Oeler Industries, Inc.
So
you've decided you're going to invest in some home theater equipment. You head
off to the dealer's showroom and are blown away by the top of the line system
and lay down $5000.00 bucks and head home. Brimming with excitement, you spend
hours mounting and installing everything until the big moment when you drop in
your favorite DVD only to find that you are missing the smooth and dramatic response
you heard at the store. So what's missing?
The bottom line is that once
you've reached midrange quality in your AV equipment, the weakest link is going
to be the room acoustics, the most overlooked aspect of setting up a home theater.
When you are more than a few feet away from the speakers, you are listening from
what is called "far field", and the sound is actually coming to you
indirectly from the room and not the speakers. Because the speakers are spreading
sound in many directions, the room acts like a big filter, exaggerating some sounds
while softening others. Now where do you start? If it is within your budget,
it would be well worth the investment to hire a professional acoustical consultant,
but if you need to keep your costs down, you can certainly improve your room acoustics
by following a few simple rules:
- If possible
address any excessive outside noise, (HVAC, traffic, footsteps, etc.).
- Treat
20% to 40% of your wall space with acoustical absorption panels to reduce reverberation,
flutter, and echoes.
- Add absorptive bass traps to corners
to reduce low frequency build up.
There are many noise control products
to keep unwanted sounds from entering your home theater. Duct Silencers and pipe
and duct lagging to reduce HVAC noise, vinyl noise barrier and isolation clips
to decouple walls and ceilings thus interrupting the transmission of sound waves,
as well as acoustic doors and door seal kits. The goal here is to improve speech
intelligibility in the movie's soundtrack by lowering the signal to noise ratio
(that is, the relative strength of the speech vs. the background noise).
Acoustic panels and bass traps come in a wide variety of materials and price ranges.
There are custom fabric wrapped panels that can be made to seamlessly integrate
with the room's décor, as well as prefab panels and out of the box kits.
The main thing to remember is that a mediocre sound system in a well-tuned room
will outperform a top of the line sound system in a poorly tuned room. Jack
Kress
Oeler Industries, Inc.
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