Broadband Sound Absorption and Energy Harvesting by a Graded Array of Helmholtz Resonators

Abstract

In both experiment and simulation, we demonstrate a graded array of Helmholtz resonators (HRs) with cross-linked polypropylene (IXPP) ferroelectret films on the inner walls of cavities, which can realize both sound absorption and energy harvesting within 300–800 Hz. This dual-function graded array contains nine HRs with different sizes, which can offer a broadband working frequency and absorb part of acoustic energy. The unique ability of IXPP ferroelectret films can be used to efficiently harvest sound energy during resonant performances. An electric circuit is designed for collecting electrical signals of each branch individually. The average values of sound absorption coefficient and output power are about 0.81 and 1.43 nW in the range of 300–800 Hz with an input sound pressure level (SPL) of 100 dB in experiment, respectively. Our results enrich the fundamental techniques of both sound absorption and acoustic energy harvesting (AEH), which can pave a way for designing acoustic device in the field of sound absorption and energy conversion for future engineering application.