Exhaust silencers, also known as mufflers, are devices that are installed in the exhaust system of a heavy goods vehicle (HGV) to reduce the noise produced by the engine. The exhaust silencer works by using a combination of sound-absorbing materials and internal chambers to dissipate the energy of the exhaust gases and to reduce the noise that is emitted from the tailpipe. Exhaust silencers typically consist of a cylindrical or rectangular-shaped housing that is made of metal or another durable material. Inside the housing, there are one or more chambers or tubes that are filled with sound-absorbing materials such as fiberglass or steel wool. As the exhaust gases pass through the silencer, the sound-absorbing materials and internal chambers help to reduce the noise level of the exhaust. Exhaust silencers are important for the HGV as they help to reduce the noise pollution caused by the engine and make it more pleasant for the driver and the surrounding environment. It also helps to meet the noise level regulations of different regions and countries. Exhaust silencers should be inspected and serviced regularly, as recommended by the vehicle manufacturer, to ensure that they are working properly and that the vehicle's noise level is not exceeding the legal limit. Worn out or damaged silencers can cause the vehicle to produce excessive noise, which can be a violation of the local noise level regulations.