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Synthesizing coherence loss by atmospheric turbulence in virtual microphone array signals
Dorothea Lincke1, Timo Schumacher2, Reto Pieren1
1Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
The Journal of the Acoustical Society of America
|February 2, 2023
Summary
Atmospheric turbulence distorts aircraft noise measurements from phased microphone arrays. A new virtual method simulates turbulence effects, improving array design and algorithms for clearer noise source analysis.
Area of Science:
- Acoustics
- Aerospace Engineering
- Atmospheric Physics
Background:
- Phased microphone arrays are vital for aircraft noise source analysis.
- Atmospheric turbulence degrades beamforming accuracy by causing signal incoherence.
Purpose of the Study:
- To develop a virtual synthesis method simulating atmospheric turbulence effects on microphone array measurements.
- To enable optimization of array designs and algorithms in a controlled environment.
Main Methods:
- Modeling sound propagation through turbulence using Ostashev/Wilson and von Kármán models.
- Calculating spatial coherence with parabolic equations for inhomogeneous, isotropic turbulence.
- Simulating signal decorrelation via time-varying mixing and auralization for propagation effects.
Main Results:
- Virtual environment accurately reproduces turbulence-induced coherence loss.
- Increasing turbulence strength leads to reduced sound levels and blurred images.
- Demonstrated impact of meteorological conditions on beamforming and deconvolution.
Conclusions:
- The proposed method effectively simulates turbulence effects on phased microphone arrays.
- This virtual approach aids in optimizing array performance and noise analysis algorithms.
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