The resistant muffler is composed of tubes and chambers with abrupt interface, as if it is an acoustic filter, similar to an electrical filter, each chamber with tubes is a mesh of the filter, and the air quality in the tubes is equivalent to Electrical inductance and resistance, called sound quality and sound resistance. The volume of air in the chamber is equivalent to an electrical capacitance, which is called sound compliance. Similar to an electrical filter, each tubed cell has its own natural frequency. When sound waves containing various frequency components enter the first short pipe, only sound waves of certain frequencies near the natural frequency of the first mesh can pass through the mesh to reach the second short pipe, while other frequencies Sound waves cannot pass through the mesh. It can only be reflected back and forth in the small room, so we call this structure with filtering function for sound waves as acoustic filter. Select the appropriate tube and chamber to combine. The noise of certain frequency components can be filtered out, so as to achieve the purpose of noise reduction. Resistive mufflers are suitable for eliminating medium and low frequency noise.