Sound absorption by textile resonators

Karsten Neuwerk,Götz T Gresser,Michael Haupt

doi:10.21595/vp.2020.21309

Abstract

Since the first usage of absorbing structures to modify architectural acoustics the dampening of low frequencies has proven to be a difficult issue. Due to the rise of the population and concentration of said population in urban areas, also known as urban densification, the noise level has risen over the last years. A long-term exposure to noise can lead to serious health problems such as high blood pressure and sleep deprivation. The omnipresent sound in urban areas has a direct impact on the personal well-being. Currently used broadband absorbers work well in a frequency range from 300 Hz to 5 kHz. The dampening of frequencies below 300 Hz, especially below 200 Hz, requires large voluminas due to the wavelength and the absorbing mechanism. To achieve absorption of low frequencies a textile resonator with multiple absorbing mechanisms is proposed. The conversion of energy from the acoustic pressure field in mechanical oscillations as well as heat provides the possibility for efficient absorbers without large voluminas. Compared to common membrane resonators, which similar to Helmholtz resonators use a closed cavity behind the membrane, the textile resonators do not need a closed cavity to generate friction and visco-thermal losses.

Highlights

The ongoing urbanization that took place in the last decades led and still leads to a higher density in population and leading to more noise pollution due to growth in building construction as well as public and private transport [1]
The statistic evaluation of the FFT-spectrum-analysis determines that an added mass on the textile surface has a high impact on a resulting resonance frequency
Three different types of resonances occur, whereby these resonances broaden the bandwidth of the absorption capability that already can be achieved with textile resonators

Summary

Introduction

The ongoing urbanization that took place in the last decades led and still leads to a higher density in population and leading to more noise pollution due to growth in building construction as well as public and private transport [1]. Given the fact that noise can lead to higher stress levels followed by serious health problems, this is an alarming development. A long-time exposure to high noise levels can lead to stress, high blood pressure, insomnia, impairment of cognitive performance in children and other severe diseases [3,4,5,6]. The urban densification is a health risk for humankind. The solution for this task is the reduction of noise either by reducing the sources or by increasing the effectivity of sound absorption in the relevant environment

Results

Discussion

Conclusion