Unidirectional solutions for active noise control in ducts

Vesa Välimäki, Jari Kataja, Marko Antila

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific


    This paper reviews our recent work on active noise control (ANC) in air-conditioning ducts using unidi-rectional detectors. The system comprises of a feedforward FIR controller and a duct with a pair of reference microphones. This paper focuses on the design of a unidirectional reference detector that can be used for reducing the acoustic feedback. A microphone pair is used and the obtained two signals are filtered appropriately before summing them up. We discuss and compare design methods for digital filter structures whose task is to cancel the upstream going antinoise signal and at the same time amplify the downstream going noise signal. Design techniques are based on optimized fractional delay filters and a two-channel weighted least-squares method. A structure composed of a parallel connection of FIR filters, which we optimize using a weighted least-squares method, shows the best directivity properties among the cases considered in this study.
    Original languageEnglish
    Title of host publicationInternoise 2001: Proceedings of the 2001 International Congress and Exhibition on Noise Control Engineering
    PublisherInstitute of Noise Control Engineering
    Number of pages6
    ISBN (Print)90-806554-2-2, 90-806554-3-0
    Publication statusPublished - 2001
    MoE publication typeB3 Non-refereed article in conference proceedings
    EventInternational Congress and Exhibition on Noise Control Engineering, Inter-Noise 2001 - The Hague, Netherlands
    Duration: 27 Aug 200130 Aug 2001


    ConferenceInternational Congress and Exhibition on Noise Control Engineering, Inter-Noise 2001
    CityThe Hague


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