ACTIVE NOISE ATTENUATOR IN DUCT

摘要

The active noise control system in duct by direction separation of sound wave is capable of performing sound wave separation calculation in a frequency area to obtain an accurate sound voltage signal in the frequency area and thus using the separated result as a reference signal of an adaptive control algorithm and an error signal. The active noise control system comprises: microphones(1,2) for sensing sound wave in the ducts; a low frequency pass filter(3); A/D converters(4,4') for the output of the lower frequency pass filter(3); a sound wave separator(5); an FET(6); a frequency area adaptive filter(9) and a time area filter(13) each for inputting the reference signal(7) and an output signal(8) to generate a control sound; a frequency area adaptive filter(12) and a sound feedback corrector(14) each for inputting the error signal and an output signal; a D/A converter(15); and a low frequency pass filter(3').