The muffler is a small part in the exhaust system of a vehicle. Mufflers perform a very crucial job – they reduce the noise coming from the combustion engine. One only has to start a car without a muffler to know how important this is. The noise level of the engine is very high and they affect the eardrum.
Sound goes in a wavelike pattern. When the exhaust valve opens intermittently and spews smoke with pressure, the same wave motion is produced within the exhaust pipe producing a lot of sound.
How it works
Sound amplification and reduction
The interference of two sound waves can either amplify them or reduce or nullify them. If two waves combine in phase, it is called a constructive interference. And if they combine out of phase, it is called destructive interference. When two waves that are out of phase hit the ear, nothing will be heard. The muffler uses this technique to reduce sound.
Inside a muffler
The muffler is constructed in a way that it reflects the entering sound waves multiple times so that they interfere with each other.
Inlet
The exhaust gases and sound waves enter the muffler through the inlet.
Resonator chamber
The resonator chamber is where the sound waves cancel themselves out. The waves as they enter, go all the way till the anterior end, strike the surface and return back. When they return back, through a hole, they reach a chamber called the resonator chamber. The resonator chamber has specific measurements and holds a specific volume of air, to produce waves of a particular wavelength to cancel other waves. The length of the resonator is adjusted so that, the higher pressure waves that get reflected off the wall, and meet with the low pressure waves just entering the chamber.
Perforations
There are perforations on the tube that leads from the inlet as well as the tube that carries the exhaust outside the muffler. When the waves enter the first pipe, they are highly pressurized and thus have a high amplitude. The perforations absorb some amount of the shock created by the waves and thus reduce their intensity.
Back-pressure reducing mufflers
When mufflers reduce back-pressure, they also create an impediment in the passage of exhaust gases. This is because the exhaust is routed through a number of turns and reflections by which the wavelength of their sound is reduced. The engine faces a little pressure backwards, and some efficiency is also lost because the exhaust is not evacuated without resistance.
There are mufflers that reduce back pressure. These mufflers are designed in such a way that they do not offer too much resistance. To put this into effect, these mufflers use only the technique of absorption. But, back-pressure reducing mufflers don't reduce noise as effectively as normal mufflers do.
Sound goes in a wavelike pattern. When the exhaust valve opens intermittently and spews smoke with pressure, the same wave motion is produced within the exhaust pipe producing a lot of sound.
How it works
Sound amplification and reduction
The interference of two sound waves can either amplify them or reduce or nullify them. If two waves combine in phase, it is called a constructive interference. And if they combine out of phase, it is called destructive interference. When two waves that are out of phase hit the ear, nothing will be heard. The muffler uses this technique to reduce sound.
Inside a muffler
The muffler is constructed in a way that it reflects the entering sound waves multiple times so that they interfere with each other.
Inlet
The exhaust gases and sound waves enter the muffler through the inlet.
Resonator chamber
The resonator chamber is where the sound waves cancel themselves out. The waves as they enter, go all the way till the anterior end, strike the surface and return back. When they return back, through a hole, they reach a chamber called the resonator chamber. The resonator chamber has specific measurements and holds a specific volume of air, to produce waves of a particular wavelength to cancel other waves. The length of the resonator is adjusted so that, the higher pressure waves that get reflected off the wall, and meet with the low pressure waves just entering the chamber.
Perforations
There are perforations on the tube that leads from the inlet as well as the tube that carries the exhaust outside the muffler. When the waves enter the first pipe, they are highly pressurized and thus have a high amplitude. The perforations absorb some amount of the shock created by the waves and thus reduce their intensity.
Back-pressure reducing mufflers
When mufflers reduce back-pressure, they also create an impediment in the passage of exhaust gases. This is because the exhaust is routed through a number of turns and reflections by which the wavelength of their sound is reduced. The engine faces a little pressure backwards, and some efficiency is also lost because the exhaust is not evacuated without resistance.
There are mufflers that reduce back pressure. These mufflers are designed in such a way that they do not offer too much resistance. To put this into effect, these mufflers use only the technique of absorption. But, back-pressure reducing mufflers don't reduce noise as effectively as normal mufflers do.
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