How a silencer works

If it was not silenced the exhaust noise of a motor vehicle would have an ear-splitting loudness. Silencers use two techniques to provide an effective remedy here. Absorption and reflection.

In the case of absorption the sound waves in the silencer are absorbed by porous absorption wool: The sound energy is converted by friction into heat.

In reflection, obstructions throw the sound waves back or deflect them. In this way the waves meet one another and as it were mutually eliminate one another.

The result can be heard: The exhaust noise is reduced by around 50 dB (A). And the sound pressure by a factor of 300.