Investigation of low frequency duct noise reflector using shunted speakers

A new duct noise control device is introduced based on Herschel-Quincke (HQ) tube and electro-mechanical coupling. The system consists of the main duct segment and one set of shunted loudspeaker, which functions as a side-by tube in traditional H-Q tube. The acoustic waves imposed on the first loudspeaker can be transmitted to the other via the connection circuit immediately, which represents a fast track when compared with the wave transmission via the fluid medium in the main duct. A simplified plane wave model is built and finite element modeling is also developed for more quantitative studies. The analytical results are verified through numerical approaches. Typically, the transmission loss has two or more resonance peaks. Contrasting with traditional reactive silencer, low frequency noise reflection can be achieved in this new device.