Where are the silencers on most cars

silencer

Absorption and reflection of sound

The propagation of sound can be reduced or prevented in two ways:

Soundproofing or absorption

During absorption, sound waves are converted into heat by friction in a sound absorbent. The sound-absorbing substances are mostly a porous material in the form of continuous glass fibers that is harmless to health.

Sound attenuation or reflection

In sound attenuation, reflective obstacles are placed in such a way that they prevent the sound from spreading. These can be changes in cross-section or pipe deflections that reflect the sound.

Modifications of these types of sound attenuation are interference and throttling systems. In the case of damping by interference, the exhaust gas flow is divided and guided into pipes of different lengths. The sound waves therefore have to cover distances of different lengths. To meet they come back on top of each other, they overlap and cancel each other out. With throttling, perforations and pipe constrictions ensure that the exhaust gas flow is broken up and dampened.

Modern silencers usually work with a combination of different damping mechanisms - either as separate silencers (middle and rear silencers) or in a single combined silencer.