(1) anechoic performance, namely, the muffler and the spectrum characteristics. To represent the muffler transmission loss and insertion loss is usually used. In field test, can also use the exhaust port (or inlet end to represent the acoustic difference). Spectral characteristics of muffler with octave or 1 / 3 octave band noise figures.
(2) the aerodynamic performance, namely the loss of resistance and resistance coefficient. Loss of resistance muffler is usually full pressure muffler entrance and exit difference to represent, resistance coefficient from the muffler dynamic pressure and resistance loss calculated. Install muffler in the airflow channel, will inevitably affect the aerodynamic performance of equipment. If only consider the muffler performance while ignoring the aerodynamic performance, and in some cases. The muffler is likely to greatly reduce the equipment efficiency, and even can not use.
(3) structure which has the same performance, muffler attenuation performance and aerodynamic performance, the smaller size, the cheaper the price, service life is long.