As part of the exhaust system, the muffler is responsible for dampening engine noise and releasing vehicle emissions into the environment. All mufflers are designed to revert the pressure and emissions produced in the combustion process and keep them from entering the cabin of the vehicle. Mufflers are commonly made of steel and coated with aluminum. There are two types of mufflers in vehicles. The first type of muffler utilizes resonating and expansion chambers to reduce noises as a result of the engine combustion process. When sound waves move through this type of muffler, high frequency waves collide with low frequency waves and cancel each other out, thereby eliminating noise. The other type of muffler utilizes a perforated pipe, containing metal, fiberglass, or another sound-absorbing material. Maintaining optimal muffler performance is a must if you aim to protect your passengers from harmful emissions while keeping the operation of your vehicle relatively quiet.