Broadband acoustic insulation via gradient impedance boundary waveguide

Abstract

In this work, we analytically and experimentally present a perfect and broadband acoustic insulation waveguide composed of gradient impedance boundaries. With these designed impedance boundaries, the incident plane wave will be converted into the surface wave mode and be absorbed or reflected back. The transmission rate reaches nearly zero in a broadband (1800–7000 Hz, typically), and the bandwidth is adjustable to fit different noise spectra. Our results may contribute more possible designs for noise reduction challenges in the waveguide.