Vehicle acoustics and damping help needed!

[SonicQ]

I am in the process of designing and installing a relatively high end car audio competition system. My question for you guru's is.

A) What would be my best bet in a car environment of creating a sound barrier between the interior of the car and exterior noises (including engine, road, and suspension noise). Obviously wind noise is a factor as well.

B) What would be my best bet to deaden the panel vibrations and metal resonances, etc.

C) What type of materials, how much, and in what order of placement and location would you suggest?

D) What would be my best way to diffuse the sound within the vehicle with taking up the drivablity of the vehicle?

I have come to the conclusion thus far, that a hi-temp mastic, asphalt based material and/or rubber (in a spray form such as "bedliner" and "undercoating&quot will provide the best form of mass loading available, to lower the resonant frequency of each panel in order to prevent the overall vibrations within the vehicle. With a layer of "carpet jute" or the like as a mass barrier type material over that, to cut down on the road noise, and transmitted noise. Also considering a form of diffusers to place within the car (Ceiling rear hatch area, etc.)

Any help regarding this would be greatly appreciated. Thank-you in advance!

-Klifton [sig][/sig]

 

[34V]

As we all know vibration is what we want to kill here. One thing that has been use-full to me the use of silicon caulk. It absorbs virbations quite effectivly. I would use this at almost every joint / connection point inside your car. (I.E. any place that can vibrate)
Also if your really getting in to this put supports in the door panels,under-body,ect. to strengthen the areas to reduce sound from passing though. Another thing is to use Medium Density Fiber board in these areas as in all your speaker boxes, (it has a effect of not resonating due to the random layout of the fibers and the qualitys of wood it's self)you might even sand-wich silicon caulk between two peices of fiber board for even more sound control. The use of sound absobing materials in the spaces between the doors, dash,ect. helps also. The trick is to hide all this stuff and make it look nice.
I hope this helps-