Virtual Error Approach to Active Sound Control in Transformed Domains

A virtual error approach is proposed to attain direct adaptive active sound control using multiple microphones and loudspeakers, when the second path dynamics (room transfer matrix) is uncertain and changeable. To reduce the control errors, two kinds of virtual error vectors are introduced and are forced into zero by adjusting two or three adaptive FIR filter matrices in an on-line manner, by which the convergence of the actual control errors to zero can be attained. The proposed virtual error approach in time domain has high computational burden, so the scheme can also be implemented in frequency domain and wave field domain using a loudspeaker array. By using their orthogonality, computational load can be reduced. The effectiveness of the virtual error approach in the transformed domains is examined in numerical simulations