A TRAVELLING WAVE APPROACH TO ACTIVE NOISE CONTROL IN DUCTS

✍ Scribed by J. Yuan; K.-Y. Fung

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 243 KB
• Volume: 219
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1006/jsvi.1998.1885

✦ Synopsis

This paper presents a new scheme for active noise control (ANC) in ducts. It uses three pressure sensors to measure and separate the far field wave into the incident wave from the primary noise source, the reflected wave from the duct outlet, and the anti-sound wave generated by the loudspeaker. The transfer functions of wave components, measured between sensor locations, are simple delay factors with possible attenuation. The simple form of transfer functions makes it easier to design ANC schemes in practical applications. Applied to adaptive ANC, the adaptation process is simplified when the error path is equivalent to a delay factor. As a result, the new scheme identifies and compensates for the transfer function of the loudspeaker and the power amplifier without introducing an annoying pseudo random signal into the duct. Effectiveness of the scheme is demonstrated by direct time-domain numerical simulations.