A side branch resonator for attenuating sound waves of first and second frequencies, the side branch resonator comprising a discharge branch; a resonator branch; an inlet branch flow connected to the discharge branch having an axis, the resonator branch having a wall which defines a resonator branch interior; the resonator branch having an open resonator branch end and a closed resonator branch end; the resonator further comprising an attenuation member for attenuating the first frequency sound waves. The attenuation member is located in the resonator branch interior a first distance from the axis and upstream from the resonator branch closed end. The closed resonator branch end is located a second distance from the axis to provide attenuation of the second frequency sound waves.
展开▼
