The muffler is located in the exhaust system between the exhaust manifold and the exhaust outlet.
It is usually made of sheet steel, coated with aluminum to reduce corrosion. Some are made of stainless steel.
A muffler contains perforated pipes, baffles and resonance chambers.
Many also contain sound-absorbing material such as fiberglass or wire wool.
The muffler slows down the gases and breaks up the pulsating sound waves, and so reduces the noise.
It must cause as little restriction as possible. Poor design can cause excessive back-pressure that will slow down the escape of the exhaust gases and reduce engine performance.
Some mufflers combine baffles and pipes to change the flow of gases without restricting them. Gases enter through the inlet and must reverse their direction of flow before they exit through the outlet. This is called a reverse-flow muffler.
Some mufflers use double outer-skins to minimize heat and noise transmission.
Some exhaust systems use a resonator as well as a muffler. It looks like a muffler but it usually has a straight-through design and it contains sound absorbing material. It’s designed to remove types of sound that mufflers can’t remove.