Q. I heard that sound deadening my car will actually keep the bass in the car. I want my vibrations to stop, but how on earth will I ever pull mad trim if the ladies can't hear me coming from 3 blocks away?
A. Using a vibration damper on you car will in fact help keep the sound in the car.
Without sound damping the typical car cabin will lose 2-5 dbs of "sonic energy” because the bass energy is being used to flext the panels.
Damping the vibrating panels makes them stronger; this makes it harder for them to vibrate with the given amount of energy your subs produce. Since the energy is no longer wasted on moving those panels it is kept in the car.
Bass in a car will force energy out of the car through the most efficient means possible, thus being the week areas of the car, thus being the thin panels of the car, thus...vibrations and panel flex.
Think of it like a sub woofer enclosure. Put a 15 inch sub with 1000 watts in an enclosure made out of 3/4 inch MDF. Then put the same sub in an enclosure made out of cardboard. Where does the energy go in each? Where is the energy lost in each? The solid box will hold the energy and force it out the port or the sub. The flimsy box will lose energy everywhere since the cardboard is far less strong than the sub woofer.
More of the energy is kept in a dampened car, making it louder in the car, and less loud out side of the car. However, once you roll the windows down there will be more bass energy escaping through the windows. The dampened car with the windows rolled down will be louder since the energy is redirect into the car and out the window.
The undampened car will not project as much bass energy outside the car because it is wasting some of it by flexing the panels. You will however have louder vibrations than the dampened car and the total energy will be about the same. But in the real car audio world we don’t care about energy. We care about the bass.
Dampen your car to make it more efficient at projecting bass out your windows.