With the resurgence of active noise control in the past two decades, the design and implementation of optimal noise cancellers has been a topic of considerable research. Recently, much of the investigation is focused on fixed controllers that rely on the robustness of closed loop systems to deal with poorly parameterized or changing plants. Many acoustic systems employ internal model controller...

Active noise control (ANC) systems have been increasingly researched and developed [1]. The use of the modified filtered-x structure for ANC using finite impulse response (FIR) adaptive filtering [2] will be assumed in the rest of this paper (Fig. 1). The multichannel versions of the filtered-x least-mean-square (FX-LMS) and the modified FX-LMS (MFX-LMS) algorithms are the benchmarks to which m...

There are two ways to implement frequency domain filtered x LMS (FXLMS) algorithms. The first carries out both control signal generation and control filter updating in the frequency domain, and the second involves implementation of the control filtering in the time domain and updating of the coefficients of the control filters in the frequency domain. Most active noise control literature is foc...

This paper proposes an active noise control algorithm for periodic disturbances of unknown frequency. The algorithm is appropriate for the feedback case in which a single error microphone is used. A previously proposed algorithm for the rejection of sinusoidal noise sources is extended for the cancellation of multiple harmonics. Unlike many other approaches, the estimates of the frequencies of ...

Global active noise control has been obtained on the tonal noise from a small centrifugal blower, similar to those used in laptop computers. Compact control systems were investigated for two configurations. The blower was mounted in both a short rectangular duct and in a mock laptop case that was modeled as a two-dimensional rectangular enclosure. Secondary sources and error sensors were locate...

This paper deals with the practical aspects of the design of two active noise control (ANC) systems to attenuate low frequency noise. In the first instance, a hybrid passive-active control system to reduce the noise radiated by a small generator has been designed. A SISO ANC system, in a side branch of the exhaust tube, attenuates some of the harmonics of the lowfrequency exhaust noise as much ...

In this paper existing classical and advanced techniques of active acoustic noise cancellation (ANC) in ducts are collected and compared. The laboratory plant used in experience showed a linear behaviour and so the advanced techniques were not used. Due to delay on the plant, the feedback classical techniques could not be applied. The best results were obtained with the modified filtered-refere...