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Scientific papers

2026-online first

Preliminary analysis of an in-situ measurement system for nor-mal-incidence absorption coefficient using a microphone array

DOI
https://doi.org/10.3280/riaof-2026oa21889
Submitted
gennaio 19, 2026
Published
2026-04-20

Abstract

Acoustic characterization of materials is crucial to evaluate their sound-absorbing properties under real conditions. Standard methods, such as the impedance tube (ISO 10534-2) and the reverberation chamber (ISO 354), show limitations for in-situ measurements. This study presents an innovative approach to estimate the normal-incidence absorption coefficient using a low-cost 4×4 microphone array. The method computes normalized acoustic impedance and reflection coefficient from microphone pairs, with free-field calibration. The system covers 100 Hz–5000 Hz through variable spacers and reduces operational complexity compared to traditional techniques. Numerical validation via finite element modelling and experimental tests in anechoic chamber show good agreement with analytical models and standards, with deviations comparable to the reproducibility of standardized methods. Results confirm the robustness of the approach against geometric variations and edge effects, enabling fast and reliable measurements in real environments.

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