Originally Posted by
Jstas
Your idea totally negates the laws of physics. Audible sound does not pass through objects. It is reflected off of objects (i.e.: echos). The reason you can hear sound through your door panels is because the sound is vibrating the door panel at the same frequency that it is hitting the door panel. This causes the door panel to vibrate which moves the air on the other side of the door panel where you are. That vibrating air then, in turn, vibrates your ear drum where you brain translates that vibration to sound. Dampening occurs when the mass of the object the sound is hitting is too great for the limited energy in the sound to move adequately and transfer that sound.
Dynamat works by changing the mass of the object it is attached to and thereby dampening it's reaction to sound energy in the environment. If takes, say, 10 watts of power to vibrate the door panel and you add Dynamat which increases the mass of that door panel by 30%, it now takes, say, 13 watts to vibrate that door panel. That means that your 10 watts of power will now not be able to vibrate that door panel as much as it did before. It dampens the vibration. It doesn't eliminate it.
Dynamat, by the way, is made from butyl rubber and aluminum which is cheaper than the vinyl products. Also, add Dynaliner, made from polyether, urethane based foam and you get Dynamat Extreme with a material composition very similar to your linked materials. Dynamat Extreme is made from materials with similar properties to the close cell vinyl that you believe is the hold grail of sound deadening.
The materials your are discussing diffuse sound. They don't dampen vibrations because they do not add substantial weight to the door panel. At least not as much as Dynamat would add. They may tame resonances but they do so through sound diffusion. It's the same principle behind yelling with your hands cupped around your mouth versus yelling with a blanket over your head. The blanket doesn't add any mass to your vocal cords but it dampens the sound by diffusing the energy with air flow resistance. Slow the air flow down, you lower the energy of the sound. That's diffusion.
As far as "blocking" the sound, you already do that with the sheet metal of your car. That glass does a bunch of blocking too. But glass is rigid to the point where it's brittle. Most crystalline structures are. Rigid structures vibrate like a Chihuahua in Siberia. The also transfer sound easily too. They also reflect sound. Just because you can hear stuff inside and outside the car doesn't mean the sound deadening didn't work. If you're going to reference Mercedes or Lexus and so on concerning sonically non-transferring glass, look up the glass they use. It's laminated and framed to reduce vibrations and ensure an adequate seal around the glass from the weatherstripping to minimize air leaks.
Yeah, "back to class" is right. Why don't you pay attention to your teachers instead of regurgitating what some sales monkey or marketing flunky posts in a website about a product they are trying to sell you to bilk you out of your hard earned money. You might actually learn something that's not only true but useful.
