There are many small holes on the silencer, the air holes vortex energy consumption, noise silencer acoustic shock absorbing material. 

Generally by the exhaust pipe silencer, connecting nut, silencer tube core barrel and several components. Oil asbestos gasket fitted in connection threaded sleeve in order to prevent leakage of the exhaust pipe and silencer interface between the barrel. Silencer barrel welded 7 partition, will be divided into eight Silencer silencer cylinder chamber (seven expansion chamber and a resonant cavity) in the cylinder core inverted triangle above a diversion channel and many holes, when the engine exhaust gas temperature when a high speed through the exhaust pipe into the silencer, the silencer due to the cross-sectional area of the cylinder increases, the gas flow can be expanded, reducing the flow rate, the pulsation noise can be attenuated strong. When the airflow continues to flow through each of the expansion chambers, since the spacer block, the air flow only from the orifice in the partition, and the cylinder core by the sudden flow then be compressed into a plurality of small streams, and then to sudden expansion, mutated so many times, the sound can be greatly attenuated, and thus play a role in reducing the exhaust noise. 

Silencer their works can be divided into resistive silencer, silencer and impedance composite silencer. 

Resistive silencer using the sound absorbing material is mainly the noise reduction, the sound-absorbing material is fixed in the pipe wall or the airflow in the pipe arranged in a certain way, when the sound waves enter the silencer, the sound can be absorbed most played silencers role resistive silencer advantage is that the silencer in a wide range of high frequency, especially for high frequency sound silencer prominent role. The disadvantage is that the shorter the life of the high-temperature steam and sound-absorbing material on the erosion of gas. Commonly used in home, office air conditioners; large wind tunnel, between the jet engine test places. 

Also known as acoustic silencer filter, it is divided into resonant, expansion chamber and interferometric several. The simplest type is connected to the expansion chamber in the flow cross section of the larger section of the channel tube thick tube, but its terminal is a thin tube to adjust the expansion chamber (bassoon) to vary the cross-sectional length of buckle and interference properties of the reflected sound waves, thereby changing silencer silencer and maximum frequency. It differs from resistive silencer that none of them placed sound-absorbing material, the advantages silencer is a simple structure, high temperature gas corrosion resistance, good low-frequency performance silencer. The disadvantage is that the silencer narrow band, mainly used in automobile engines and other piston engine intake and exhaust ports. 

Integrated impedance composite silencer made the first two advantages. Both in its internal resistive sound-absorbing material, but also resonant cavity, such as resistance to the expansion chamber filter components, it is a good silencer results in a wide frequency range.