Silencer (Muffler)

Cars often have a middle and a rear silencer. They use chambers and absorbing material. Some have flaps to change the sound. Aftermarket silencers must meet noise rules and carry type approval markings in many countries. Short trips leave condensation in silencers, which accelerates internal rust, so rear boxes often fail from the inside first. Some cars use electronic sound generators to shape the engine note heard in the cabin.

Sound waves are reflected and absorbed.

Rusted silencers rattle or become loud. Removing silencers is illegal.