A low-frequency multiple-band sound insulator without blocking ventilation along a pipe

Abstract

It is challenging to insulate sound transmission in low frequency-bands without blocking the air flow in a pipe. In this work, a small and light membrane-based cubic sound insulator is created to block acoustic waves in multiple low frequency-bands from 200 to 800 Hz in pipes. Due to distinct vibration modes of the membrane-type faces of the insulator and co-action of acoustic waves transmitting along different paths, large sound attenuation is achieved in multiple frequency-bands, and the maximum transmission loss reaches 25 dB. Furthermore, because the sound insulator with a deep subwavelength size is smaller than the cross-sectional area of the pipe, it does not block ventilation along the pipe.

Wave Attenuation in 1-D Viscoelastic Phononic Crystal Rods Using Different Polymers

“…Artificial composites, known as phononic crystals (PnCs) and/or mechanical metamaterials, are structures designed to achieve unusual properties and applications, such as vibration control 1,2 , acoustic barriers 3,4 , wave manipulation (e.g., guiding, focusing, imaging, cloaking, and topological insulation) 5,6 , energy harvesting 7 , and negative Poisson's ratio 8 . They are typically composed by periodic arrays of inclusions embedded in a matrix 9,10 to open up band gaps arising from Bragg scattering and/or local resonance 11 .…”