A boundary element method based near field acoustic holography in noisy environments

Area of Science:

• Acoustics
• Signal Processing
• Numerical Methods

Background:

• Noisy environments complicate acoustic wave analysis, including radiated, incident, and scattering waves.
• Accurate acoustic measurements are crucial for understanding sound sources and propagation.
• Near field acoustic holography (NAH) is a powerful technique for acoustic source identification.

Purpose of the Study:

• To develop a robust method for recovering free field acoustic quantities in noisy environments.
• To enhance the accuracy of boundary element method-based near field acoustic holography.
• To validate the proposed method through numerical simulations and experimental measurements.

Main Methods:

• Introduction of double-layered pressure measurement to boundary element method (BEM) based NAH.
• Separation of incoming and outgoing waves using boundary integral equations.
• Filtering of scattering waves by incorporating vibrating structure boundary conditions.
• Reconstruction of normal velocity distribution using measurements on an enclosing hologram.
• Application of Schur complement equations and Tikhonov regularization for optimized reconstruction.

Main Results:

• Successful reconstruction of free field normal velocity demonstrated even with negative signal-to-noise ratios.
• Numerical examples with representative radiators show accurate recovery of acoustic quantities.
• Experimental validation with a cubic radiator confirms the method's accuracy and practical potential in noisy conditions.

Conclusions:

• The proposed double-layered pressure measurement technique effectively recovers free field acoustic information in challenging noisy environments.
• The method offers a significant advancement for acoustic source identification and analysis using BEM-based NAH.
• The validated approach holds promise for practical applications in real-world noisy acoustic scenarios.