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Published on: March 6, 2017
Retrieval of Green's function in the radiative transfer regime
1Department of Physics, University of Illinois, Urbana, Illinois 61801, USA. r-weaver@illinois.edu
The Journal of the Acoustical Society of America
|February 1, 2013
Summary
Acoustic noise correlations reveal a new relationship between the field-field correlation function and the Green's function. This finding allows for the retrieval of important acoustic properties from ambient noise.
Area of Science:
- Acoustics
- Wave propagation
- Statistical physics
Background:
- Diffuse acoustic fields are common in many environments.
- Understanding noise correlations is crucial for remote sensing applications.
- Previous methods for analyzing acoustic fields had limitations.
Purpose of the Study:
- To establish a theoretical identity for the field-field correlation function of an imperfectly diffuse acoustic field.
- To provide a new framework for interpreting noise correlation amplitudes.
- To facilitate the retrieval of acoustic properties from ambient noise.
Main Methods:
- High-frequency approximation for acoustic wave propagation.
- Analysis of equal-time correlations in the spatial domain.
- Application of radiative transport theory to specific intensity.
Main Results:
- The field-field correlation function is shown to equal the time derivative of the Green's function multiplied by the specific intensity.
- This identity holds in a high-frequency limit with specific spatial conditions.
- The specific intensity is governed by a radiative transport equation.
Conclusions:
- The established identity offers a novel interpretation of correlation amplitudes.
- This work paves the way for retrieving attenuation, site amplification, and scattering strengths from noise correlations.
- The findings have implications for seismic and acoustic monitoring.
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