A muffler or silencer is a device for reducing the noise emitted by the exhaust of an internal combustion engine—especially a noise-deadening device forming part of the exhaust system of an automobile or motorcycle.
Mufflers are installed within the exhaust system of most internal combustion engines. The muffler is engineered as an acoustic device to reduce the loudness of the sound pressure created by the engine by acoustic quieting. Let’s explore the interesting physics behind your motor cycle’s silenser in this video from Lesics.
The noise of the burning-hot exhaust gas exiting the engine at high speed is abated by a series of passages and chambers lined with roving fiberglass insulation and/or resonating chambers harmonically tuned to cause destructive interference, wherein opposite sound waves cancel each other out.
An unavoidable side effect of this noise reduction is the restriction of the exhaust gas flow, which creates back pressure, which can decrease engine efficiency. This is because the engine exhaust must share the same complex exit pathway built inside the muffler as the sound pressure that the muffler is designed to mitigate.A cutaway muffler showing the interior pipes and chambers which reduces horsepower.Some aftermarket mufflers claim to increase engine output and/or reduce fuel consumption by slightly reduced back pressure. This usually entails less noise reduction.//wikipedia