Nissan announced a new type of sound damping that is ultra lightweight but just as effective as standard sound damping, it said.

It uses lattice structure polypropylene covered with a thin layer of plastic that Ďbounces out sound waves.í It was shown in its new Ariya concept car and the product, called meta-material, will be included in Nissan vehicles going forward.
Most OEMs use heavy rubber and fiber mats under the carpet, which increases weight.
Nissanís meta-material traps the low frequency vibrations where most road noise lies (500Hz to 1,200HZ), said CNET. Read More >>