Road noise is the unpleasant sound caused by vibrations and wind that occurs while driving, which is transmitted into the interior of the car and eventually becomes unpleasant noise. Even though it is called noise, it is just sound. If it's a sound, there's always something inside the car that makes that sound. The sound from outside the car does not directly enter the car, but always passes through something, so the floor inside the car, especially if it is a monocoque body, also serves as the skeleton, so the floor related to the inside of the car is especially important. This is the most important part due to its area. By deadening this area, the physical sensation inside the car will change considerably.