Broadband monopole emission enhancement using a dual acoustic grating

Highlights: • A dual acoustic grating with anisotropic mass density is presented. • The sound pressure level gain graph shows the broadband emission enhancement of the monopole source. • Broadband monopole emission enhancement is explained by a rigorous model. • The experiment verifies that the enhanced broadband monopole emission can be achieved by the dual acoustic grating. The enhanced broadband emission of monopole source is achieved by a dual acoustic grating with anisotropic mass density. The exact expressions among the enhanced efficiency and all the structural parameters of the dual acoustic grating are obtained through rigorous analytical model based on the radiation impedance theory. The results show that the enhanced broadband monopole emission can be realized in the dual acoustic grating through the coupling of the first and the second resonance modes. Considering the thermo-viscous dissipation, the broadband monopole emission can be enhanced through parameter optimization and the sound pressure level (SPL) gain is above 11 dB. Its bandwidth is 1060-1920 Hz and the fluctuation of the SPL gain in the frequency band is 3 dB. The sample is further fabricated and the enhanced broadband emission of monopole sources by the dual acoustic grating is experimentally verified. The study of this letter could have potential application for loudspeaker design and acoustic communication.