Air conditioner arts Fx type impedance complex muffler use superfine glass wool as impedance sound absorption, and have good muffler effect to medium high frequency. Impendance muffler is made up of the abrupt change of inside tube section and the mutual action of expansion chamber between outer tubes, and have effective muffler functions for low frequency noise and some of intermediate frequency noise. Fx type impedance complex muffler tallies with t701 standard absolutely.