Application of Cascade Connection of Recursive and Non-recursive Filters to Active Noise Control System Using Simultaneous Equations Method

Kensaku FUJII  Kenji KASHIHARA  Mitsuji MUNEYASU  Masakazu MORIMOTO  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E94-A    No.10    pp.1899-1906
Publication Date: 2011/10/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E94.A.1899
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: Noise and Vibration
simultaneous equations method,  lattice filter,  active noise control,  recursive filter,  non-recursive filter,  auxiliary filter,  

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In this paper, we propose a method capable of shortening the distance from a noise detection microphone to a loudspeaker, which is one of important issues in the field of active noise control (ANC). In the ANC system, the secondary noise provided by the loudspeaker is required arriving at an error microphone simultaneously with the primary noise to be cancelled. However, the reverberation involved in the secondary path from the loudspeaker to the error microphone increases the secondary noise components arriving later than the primary noise. The late components are not only invalid for canceling the primary noise but also impede the cancellation. To reduce the late components, the distance between the noise detection microphone and the loud speaker is generally extended. The proposed method differently reduces the late components by forming the noise control filter, which produces the secondary noise, with the cascade connection of a non-recursive and a recursive filters. The distance can be thus shortened. On the other hand, the recursive filter is required to work stably. The proposed method guarantees the stable work by forming the recursive filter with the lattice filter whose coefficients are restricted to less than unity.