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Message: <blockquote data-quote="FoxPro5" data-source="post: 4403466" data-attributes="member: 562649">Lets just say that hypothetically the tires produce 80 dB noise at 250 hz.Adding a single layer of B-quiet will probably get you 3dB in transmission loss. This is because the exterior panels (sheet metal) will conduct some amount of noise as the tire noise excites them.  Putting damping mat will help attenuate the structure borne noise by removing most of the resonance that contributes to the theoretical 80 dB, thus leaving you with 77 dB.To work that 77 dB down even further, you're probably going to want to block it from getting to your ears. More deadening mat is not the optimal choice as it's a poor product of choice for the job.Blocking noise takes mass. You can get this done in a number of ways - some are optimal for a car, some are not. A top consideration is a flexible barrier that can be conformed to the shape of the car panel.Selecting a barrier should take into account the surface mass per unit thickness. For example, something like Dynamat Extreme is about 1.5 kg/m2 per mm of thickness. Contrast this to a lead sheet which might be 10 kg/m2 per mm of thickness. The transmission loss varies by weight, but just as a rule of thumb, a barrier that's 1 lb/sqft and 1/8" thick will probably knock that noise level down by 16 dB. This is most of the commercially available mass loaded vinyl.Once you have the barrier picked out, then you need to understand that you can improve the noise blocking performance of it by mechanically isolating it from the surface. So, adding a layer of foam or something between the barrier layer and the surface can give you another 18 dB of noise attenuation (on paper.) Check the firewall in your vehicle, I bet there already is a floating barrier of sorts in place. My car, for example, came equiped with a 1/2" cotton-backed vinyl blanket over the surface of the firewall and the under dash area.So, if you start adding this up....3 + 16 + 18...you're really down to where these treatments make a major difference. To cut 80 dB nearly in half would be pretty impressive. On an A-weighted scale, you'd perceive that as being 4 times a quieter than before. However, in the real world...if you got your mic out and did the measurements...you might not find this to be the case. Nonetheless, you put some critical thinking into the project and selected the right tools for the job.</blockquote>

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