In view that the reactive muffler in the high-frequency effect is poor, and dissipative muffler
in the high frequency effect is very good, we use impedance composite design to improve the overall muffler effect.
The difference for each one-third octave band, in decibels, between the mean sound pressure level inside the reverberation room before ([SPL.sub.1]) and after ([SPL.sub.2]) the insertion of the dissipative muffler
along the test duct returned insertion loss values:
Reactive mufflers are generally used to attenuate pressure pulsations since the small holes and porous materials of dissipative mufflers
may become clogged with deposits (Soedel 2007) eventually.