Not all sound dampers are created equally. Not by a long shot. Thats like saying all steaks are created equally. Test the difference between a cube-steak from a Hungry Man dinner and a filet mignon from Stoney River....NOT the same. Sound dampers are the same way...there are differences thicknesses and qualities. Different designs are made for different results (problems).

There are also sound dampers (to help prevent rattles (distortion)) as well as sound absorbers (to help limit (or block) reflections). Sound absorbers are things like foam. Depending on the thickness, material, and makeup of the foam, it will have different results. A closed-cell foam will have different sonic effects compared to an open-cell foam. Nowdays, there are several combination foams with both a closed cell and open cell foam in 1 material. A good use for something like this is the firewall or floorboard. Put the closed cell side face down, which will help block transmission and road noise, and the open cell side face up, which will help absorb reflections. However, most typically put carpet back over the foam, which also helps.

With sound dampers, there are also a few different types. The least commong used today (but still effective) is a liquid (typically paste consistency) that you apply to panels. This transfers the vibrations of the panel into low grade heat. Not enough heat to worry about it heating up the car or panel, but still heat. Another type, and more common, is a mass loading mat. This is mostly what the mats are. They are designed to add mass (or weight) to the panel. This lowers the resonant frequency of the panel. By resonant frequency, I mean "rattle". A third type is call (sometimes) acoustical barrier or constrained layer. This is something like Dynamat Extreme. It takes the principles of mass loading (adding weight) a bit further, by adding a second layer of material (usually aluminum or similar). So, the metal of the panel you apply it to, and the otter portion of the mat are both metal. Togehter, they act as shock absorber, and will limit the amount ov vibration. Also, remember, that there is still the mass loading effect of the mat itself. So, you get a lower resonant frequency by adding weight, as well as a constraining layer to help lesses even more of the vibrations.

Older style mats are were asphalt based, which is why we had to run around town for a month with the windows rolled bown all the time...they car smelled like they just paved the trunk... Which is also why we had to burn our fingers with a heat gun...the asphalt based mat was thick and not pliable (wouldnt bend to the countours of a car door or floor panel). We heated it up so it would bend and conform to the panel. Also, they typically used heat activated adhesives. If you dont get the adhesive hot, it wont stick.

Next was the vinyl based mats. These were a progression from the basic mass loading mat, but not quite an aluminum backed constrained layer mat. They lessened the odor of the asphalt mats, but did not quite hit the mark of the aluminum backed mats. Problem was (IMO) adhesive would seperated from the mat itself over time, which would result in it falling off or releasing. They did not like to be frozen, which is not as much a problem here in Georgia as it might be in upstate New York. They became brittle over time.

So, whats the best formula? Depends.

ANY damping you do will help in some way.

I have a car with ALL of the above mentioned materials within the car. There are 7 gallons of liquid damping, boxes upon boxes of Dynamat Extreme, and about 4 different types of foam within the car. I have had Dynamat on the roof of the car for almost 10 years now with zero issues.

For those thinking putting mat on the roof af the car....the roof is typically the largest flat manel with the car...it will vibrate the most. The floor of you car has ridges in ti. This is for strength, and helps eliminate vibration (rattles). The doors and trunk area are ususally the first to get matted. Why? the energy from the speakers causes the panels to vibrate/rattle. If the door metal you mounted the speaker to was 1/4" thick...it probably wound rattle as much. Thats because it more ridgid, weighs more, and therefore has a lower resonant frequency (frequency at which it will vibrate/rattle).

Just a bit of information I picked up along the way.....