Improving active noise control in resonant fields

In active noise control (ANC), there is still room for further improvement in at least two directions: (1) how to use a finite impulse response (FIR) filter to suppress noise in a resonant field with infinite impulse response (IIR) paths; and (2) how to deal with non-minimum-phase (NMP) secondary paths. A new ANC configuration is proposed here. If the secondary path is minimum phase (MP), the new configuration is able to cancel broadband noise completely with a FIR filter. The same objective can only be achieved if one applies an IIR filter in an available ANC configuration. If the secondary path is NMP, the new configuration is able to minimize the H2 norm of the noise path with a FIR filter. Again, this result can only be achieved if one applies an IIR filter in an available ANC configuration. Analytical and experimental results are given to demonstrate the significant improvement in almost the entire frequency range of interest.