Physics-informed neural operators for the in situ characterization of locally reacting sound absorbers
This work addresses the problem of in situ acoustic material characterization for wave-based simulations, offering a more robust method compared to conventional approaches, though it is incremental as it builds on existing physics-informed neural operator frameworks.
The paper tackles the challenge of estimating acoustic surface admittance from noisy measurements by developing a physics-informed neural operator that learns from near-field sound data and frequency to predict admittance spectra and acoustic fields, validated on synthetic data showing accurate reconstruction and improved robustness to noise and sparse sampling.
Accurate knowledge of acoustic surface admittance or impedance is essential for reliable wave-based simulations, yet its in situ estimation remains challenging due to noise, model inaccuracies, and restrictive assumptions of conventional methods. This work presents a physics-informed neural operator approach for estimating frequency-dependent surface admittance directly from near-field measurements of sound pressure and particle velocity. A deep operator network is employed to learn the mapping from measurement data, spatial coordinates, and frequency to acoustic field quantities, while simultaneously inferring a globally consistent surface admittance spectrum without requiring an explicit forward model. The governing acoustic relations, including the Helmholtz equation, the linearized momentum equation, and Robin boundary conditions, are embedded into the training process as physics-based regularization, enabling physically consistent and noise-robust predictions while avoiding frequency-wise inversion. The method is validated using synthetically generated data from a simulation model for two planar porous absorbers under semi free-field conditions across a broad frequency range. Results demonstrate accurate reconstruction of both real and imaginary admittance components and reliable prediction of acoustic field quantities. Parameter studies confirm improved robustness to noise and sparse sampling compared to purely data-driven approaches, highlighting the potential of physics-informed neural operators for in situ acoustic material characterization.