A nanofibrous acoustic system based on the cavity/membrane resonance principle

Abstract

Room acoustic solutions are based on measurements of the acoustic power of the room and acoustic elements with different functions (absorption tiles, absorption ceilings, absorption bodies, diffusers, barriers). This work is focused only on absorption elements, with an emphasis on addressing lower frequencies. The goal of this research is achieved by sound absorbing means which contains a cavity resonator with a nanofibrous resonant membrane, which overlaps orifices of the cavity resonator. The design of the material is based on broadband noise. Absorption of lower frequencies is restricted to a certain extent by the final thickness of the acoustic material. A two-microphone impedance tube for determining the sound absorption coefficient was used to measure the limited frequency spectrum 100–1600 Hz. These frequencies, however, cover the area particularly focusing on middle and lower frequencies. The principle of the acoustic system consists in using combination of a cavity resonator, by which the air or other material contained in its cavities is forced into vibration upon impact of sound waves of high frequency, and a nanofibrous resonant membrane, which is forced into vibration upon impact of sound waves of low frequency. The optimal arrangement of holes inside the perforated plate, according to broadband sound absorption, has been found.