Optimization of Secondary Source Configuration for Active Noise Control in a Helicopter Cabin

The helicopter cabin noise generated by a rotating rotor is mainly characterized by discrete line-spectra in low frequency range and thus suitable for active control. In an active noise control system, the configuration of secondary sources plays a significant role for determining noise reduction. In this study, sound field reproduction methods are applied to optimize the configuration of secondary sources in a helicopter cabin using a finite element (FE) model, and to reduce the noise level at passengers’ ears. The least-absolute shrinkage and selection operator (Lasso) is used to select a reduced set of secondary sources for three harmonic frequencies, respectively. The selection of the sparsity-tuning parameter is discussed in detail under power and number constraint. The Tikhonov-regularized least squares (LS) problem is solved to smooth amplitudes of loudspeakers under power constraint.