  Active noise control (ANC) over a sizeable space requires a large number of
reference and error microphones to satisfy the spatial Nyquist sampling
criterion, which limits the feasibility of practical realization of such
systems. This paper proposes a mode-domain feedforward ANC method to attenuate
the noise field over a large space while reducing the number of microphones
required. We adopt a sparse reference signal representation to precisely
calculate the reference mode coefficients. The proposed system consists of
circular reference and error microphone arrays, which capture the reference
noise signal and residual error signal, respectively, and a circular
loudspeaker array to drive the anti-noise signal. Experimental results indicate
that above the spatial Nyquist frequency,our proposed method can perform well
compared to a conventional methods. Moreover, the proposed method can even
reduce the number of reference microphones while achieving better noise
attenuation.
