Influence of edge diffraction on the in situ measurement of impedance using microphone arrays

Eric Brandão, Efren Fernandez-Grande

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

Abstract

When measuring the surface impedance and/or the sound absorption coefficient of a material sample in situ, one of the main concerns is the sample size effect due to edge diffraction. In recent years, several in situ impedance measurement techniques using arrays of microphones have been proposed. This paper aims at analysing the the effect of edge diffraction on the in situ measurement with arrays of microphones based on a numerical simulation framework. A simplified Boundary Element Method (BEM) is used to emulate the measurement performed by two types of arrays: (i) - a double layer array, consisting of two parallel layers of uniformly spaced microphones; (ii) - a three-dimensional randomized array, consisting of an irregular distribution of measurement points within a parallelepiped. The study examines different array configurations (size and number of sensors) and sample properties (size and absorption). The wave-number spectrum is used to examine the effect of edge diffraction. The influence of edges on the estimation of surface impedance and the absorption coefficient is also analysed and compared to the estimation made with a single pressure-velocity probe.

Original languageEnglish
Title of host publicationProceedings of 2020 International Congress on Noise Control Engineering, INTER-NOISE 2020
EditorsJin Yong Jeon
PublisherKorean Society of Noise and Vibration Engineering
Publication date23 Aug 2020
ISBN (Electronic)9788994021362
Publication statusPublished - 23 Aug 2020
Event49th International Congress and Exposition on Noise Control Engineering, INTER-NOISE 2020 - Seoul, Korea, Republic of
Duration: 23 Aug 202026 Aug 2020

Conference

Conference49th International Congress and Exposition on Noise Control Engineering, INTER-NOISE 2020
CountryKorea, Republic of
CitySeoul
Period23/08/202026/08/2020
SeriesProceedings of 2020 International Congress on Noise Control Engineering, INTER-NOISE 2020

Bibliographical note

Funding Information:
The authors would like to thank Melanie Nolan for many important discussions. Also, the first author would like to thank the colleagues from Acoustic Technology at DTU-Elektro for the warm welcome during February this year.

Publisher Copyright:
© Proceedings of 2020 International Congress on Noise Control Engineering, INTER-NOISE 2020. All rights reserved.

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