Dupont Samuel, Melon Manuel, Berry Alain
Groupe d'Acoustique de l'Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, PQ J1H4W5, Canada.
LAUM UMR CNRS 6613, Le Mans Université, Avenue Olivier Messiaen, 72000 Le Mans, France.
J Acoust Soc Am. 2020 May;147(5):3613. doi: 10.1121/10.0001257.
This paper proposes two distinct methods for estimating the surface impedance Z of acoustic materials using a spherical microphone array. The first method is based on the spherical ambisonic representation of sound fields to estimate the normal particle velocity and the sound pressure at the surface of the material. The second method uses an optimization process, where the measured sound pressure field is constrained to match a theoretical model. These two methods are compared to two existing methods: the equivalent source approach and the two-microphone measurement technique. The results show a clear advantage of the microphone array methods compared to the classical two-microphone method. The measurements show an accurate reconstruction of surface impedance and absorption coefficient between 120 and 5000 Hz for various sound incidences but also show edge effect perturbations due to the limited size of the tested samples. In addition, two criteria are proposed, one estimating the noise floor level allowing the optimization of the measurement results, the other evaluating the area of accurate impedance reconstruction on the surface of the material.
本文提出了两种使用球形麦克风阵列估算声学材料表面阻抗Z的不同方法。第一种方法基于声场的球面声基表示来估算材料表面的法向质点速度和声压。第二种方法使用优化过程，其中将测量的声压场约束为与理论模型相匹配。将这两种方法与两种现有方法进行比较：等效源法和双麦克风测量技术。结果表明，与传统的双麦克风方法相比，麦克风阵列方法具有明显优势。测量结果显示，对于各种声音入射角，在120至5000Hz之间能够准确重建表面阻抗和吸收系数，但由于测试样品尺寸有限，也显示出边缘效应扰动。此外，还提出了两个标准，一个用于估算允许优化测量结果的本底噪声水平，另一个用于评估材料表面准确阻抗重建的区域。
