"WHAT THEY PROBABLY DID NOT TELL YOU
WHEN YOU BOUGHT YOUR 'HOME THEATER'!"
Years ago people used to live, eat and sleep at home and go out to the theater.
All that has changed and the results have not always been beneficial.
The following item is reprinted with the kind permission of the Acoustic Sciences Corporation.
Please see: www.asc-soundproof.com for further information.
Home Entertainment Sound Isolation
Typical residential construction is adequate at keeping low-volume, high frequency sounds (such as speech) from traveling through the rest of the household-although still not great. People talking in one room can often be heard in an adjoining room, and low muffled sounds can sometimes be heard between floors. When "frame" construction with drywall became popular in the 1950's, large sound systems and home theaters were only a futuristic dream.
Today, however, we find ourselves with an ever-increasing problem-Structure-borne Sound Transmission of low frequencies. That "Thump! Thump! Thump!" of a subwoofer going through the structure of the house and annoying everyone who's not in the listening room.
-Why Isolate the Room?
Being an acoustical design and engineering firm, we began receiving many calls for help from disenchanted homeowners. These people had recently invested in a dedicated home theater system, only later to find they had inherited an unforeseen problem-excessive bass that could be heard throughout the house.
What was expected to bring an added degree of enjoyment to the family, was now a source of discontent. Those watching the movie wanted BIG sound and with earth shaking bass. However, the rest of the family in other parts of the house couldn't stand the constant thumping and vibrations they were being forced to deal with. One party was constantly yelling "turn that thing down!". While the other party tries to inch the volume up in an effort to get that Large Cinema feel. Nobody was happy in the end.
We would hear tales of people trying everything, from pillows under speakers, egg cartons on the walls, to ropes suspending equipment off the floor. Nothing seemed to work.
In a futile search for a solution, people would call us at ASC asking about our bass traps. "Would they work?" "They do absorb bass...right?", many would ask. Unfortunately, bass traps are not the answer. Yes, they do work great at absorbing excess bass reverberation and controlling room modes, but do little in the effort to control structure-borne sound-which was the problem they now were facing.
So, what could be done? Unfortunately for them, very little-unless they were willing to undertake a major remodeling project of their home theater room. This would require a rebuild of all the walls and ceilings, an option not too popular with most.
-The Root of the Problem-
The real problem is, the room was not designed or constructed to withstand such severe sonic impacts.
When a subwoofer produces powerful low-frequency acoustic energy, that wave front travels through the room and then collides with the wall & ceiling surfaces. Upon collision, much of that kinetic energy of the wavefront is converted into mechanical (vibrational) energy, which sets the thin, flexible wall surface into vibration. This vibration is easily conducted through solid surfaces it is in contact with-such as the studs, joists and flooring. The vibration travels up and through the framing of the house--vibrating the walls, floors and ceilings as it passes them. What you get, is a quaking house full of noise. This is what is known as Structure-borne Sound Transmission.
The fact of the matter is, conventional wall & ceiling construction methods easily conduct low-frequency sound, and are poor at blocking them out.-
There are three ways to keeps sound from traveling through a structure:
Block the sound by increasing the mass (thickness & density) of the walls.
Minimize the transmission paths for vibrations and sound to travel through.
Dampen the vibrational energy.
Only Acoustic Sciences' proprietary ASC Iso-Wall System( incorporates all three of these methods.
Our system uses a double layer of gypsum to achieve twice the mass of an ordinary wall. At the same time, we minimize resonant coupling by using materials of differing density.
Path sources are reduced by "floating" the walls & ceiling off the studs, while also giving the room a tight acoustic seal at all potential openings.
Vibrations are quickly damped and the energy absorbed, by utilizing our special WallDamp material. Configured in a constrained layer method, three separate interface points are addressed to insure maximum benefit-at the stud, on the channel surface, and between the layers of drywall.
You get walls & ceilings that achieve perceptible sound volume levels SIX times * greater than standard interior walls.
With a calculated STC=60 (Sound Transmission Class), it makes our wall system one of the highest available using standard single-stud construction.
But, what truly puts the ASC Iso-Wall System in a class by itself is the remarkable ability to control and dampen low-frequencies. That boom! boom! boom! produced by sub-woofers. By incorporating our proprietary energy absorbing Walldamp material, vibrations from sub-sonic concussive events are quickly dissipated-and minimize the energy that can travel through the structure.
Other sound isolation methods simply do not measure up.
* As measured in sones, a unit of subjective loudness as perceived by human beings
How to Order-
The Iso-Wall System is sold as a complete kit, ready to be installed by your local contractor or as a do-it-yourself project. All you need to provide is the drywall and screws. Simply provide us with the dimensions of your room, and we will send a complete kit with all necessary materials and step-by-step installation instructions to complete your room. Of course, you may call one of our technical representatives at any time with questions or for assistance. Pricing for the kit materials is typically less than $3 per sq/ft.
Speak to your local ASC Distributor, or call Acoustic Sciences directly at (800) 272-8823
Please see: www.asc-soundproof.com for further information.
Stan Daniels, Editor,
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