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.
|Title of host publication||INTER-NOISE and NOISE-CON Congress and Conference Proceedings, InterNoise01|
|Publisher||Institute of Noise Control Engineering|
|Number of pages||6|
|Publication status||Published - 2001|
|MoE publication type||B3 Non-refereed article in conference proceedings|
|Event||Inter-Noise 2001 - Haag, Netherlands|
Duration: 27 Aug 2001 → 30 Aug 2001
|Period||27/08/01 → 30/08/01|
Välimäki, V., Kataja, J., & Antila, M. (2001). Unidirectional solutions for active noise control in ducts. In INTER-NOISE and NOISE-CON Congress and Conference Proceedings, InterNoise01 (pp. 1315-1320). Institute of Noise Control Engineering.