Transmission loss of a labyrinthine acoustic metamaterial augmented with multichannel feedforward active noise control

Acoustic metamaterials and active noise control are two advanced noise control treatments that can typically offer performance that exceeds that of conventional passive noise control treatments. Acoustic metamaterials utilize sub-wavelength structures to realize sound field control, whilst active noise control treatments achieve control via the introduction of additional sources driven to generate a secondary sound field that interferes in a controlled way with the original, primary sound field. This paper presents an investigation into combining these two noise control techniques, to achieve enhanced noise control over a spatial region using a hybrid device. In particular, conventional feedforward active noise control is combined with a labyrinthine metasurface and the increase in performance offered by the hybrid solution is demonstrated.