Sound regulation of coupled Helmholtz and Fabry-Pérot resonances in labyrinth cavity structures

Traditional acoustic regulations in practice are used to have major obstacles in low frequency range, for which absorbers or suppressors have thicknesses that are comparable to their working wavelength. We present an acoustic structure-based "coiling-up space" to achieve outstanding sound regulation of acoustic waves in the extremely low frequency region. The structure is composed of an open waveguide and with a spiral throat tube and a cavity. The acoustic structure excites Helmholtz and Fabry-Pérot resonances in labyrinth cavity structures, coupling of an open waveguide, which produce Fano-like resonances respectively and a broadband low-transmission spectrum in the 120-3100 Hz range. During sound regulation, the existing open waveguide can also maintain natural ventilation through the structure. In addition, the sound transmission properties are shown to be sensitive to the structural parameters, which can be used to provide a tunable sound control method for acoustic devices.