On the Determination of Acoustic Properties of Membrane Type Structural Skin Elements by Means of Surface Displacements

Abstract

The article focuses on the determination of the acoustic properties (sound transmission loss, sound absorption and transmission coefficient under acoustic plane wave excitation) of membrane-type of specimens by means of a combination of incident plane wave sound pressure and membrane surface displacement information, measuring the sound pressure with a microphone and the membrane displacement by means of a laser Doppler vibrometer. An overview of known measurement methods and the theoretical background of the proposed so-called mobility-based method (MM) is presented. The proposed method was compared with the conventional methods for sound transmission loss and absorption measurement in the impedance tube, both numerically and experimentally. Finite element model (FEM) simulation results of two single layer membrane samples of different shape configurations were compared, amongst which six different variations of the backing wall termination. Four different approaches to determine the sound transmission loss and two methods to determine sound absorption properties of the membranes were compared. Subsequently, the proposed method was tested in a laboratory environment. The proposed MM method can be possibly used to measure the vibro-acoustic properties of building parts in situ.

Acoustic Properties of Absorbing Materials

“…The measured results agree well with the predictions. The tenth paper, by Urban et al [10], focuses on the determination of the acoustic properties (sound absorption and transmission coefficients) of membrane types of specimens. The characterization was made by means of a combination of incident plane wave sound pressure and membrane surface displacement information, measuring the sound pressure with a microphone and the membrane displacement by means of a laser Doppler vibrometer.…”

Design Optimization of Three-Layered Metamaterial Acoustic Absorbers Based on PVC Reused Membrane and Metal Washers

“…Some of the characteristics identified in such materials include negative refraction [21], band gap [22], birefringence [23], and autocollimation [24]. These properties can be applied in a variety of devices covering different cases such as acoustic barriers [25], acoustic lenses [26], and acoustic absorbers [27][28][29][30].…”