Study Of Active Noise Control In A Duct

Vehicle exhaust noise is the major pollution source to external.Traditional negativecontrol method only have effect on high frequency noise which tranmit in duct,and fail tohave effect on low frequency noise,Active noise control could compensate for this problemeffectively.So this paper study on the application of using loudspeaker to suppress thenoise in a duct.By analysis the deriving principle and spectral compositon of low-frequency componentof exhaust noise,the noise signal is imitated by sinusoidal signal for harmonic componet ofperiodic noise and white noise for broadband signal.For obtain the impulse responsefunction of secondary path between the control loudspeaker and error sensor,the psudorandom series and DAQ program was made up on LabVIEW.According to the obtaineddata,the impulse response function is caculate by Winer-Hopf function.The simulationmodel was set up on Simulink based on fx-LMS algorithm,the experimental program wasmade up on PC,and success to suppress several single tone and broadband noise.For thefailure to suppress the noise in several freqency range,Disadvantage of the algorithm wasanalyzed and gives a method which filter the broadband signal in reference sensor based onadaptive line enhancer combined with the property of exhaust noise. The feedback internalmodel control method was studied,the control model was set up on Simulink, the inversemodel of secondary path derived by reference was established, and give a method whichmodify the feedback filter by PSO.The fx-LMS algorithm success to suppress the noise which fail to control by traditionalalgorithm in simulation,The noise which is under control and which is not under controlwas compared in power spectral,which proved that the fx-LMS algorithm with ALE iseffective.The experiment result also shows a good effect of suppression.