Sound field reconstruction within an entire cavity by plane wave expansions using a spherical microphone array

Area of Science:

• Acoustics
• Signal Processing
• Computational Physics

Background:

• Spherical microphone arrays effectively reconstruct enclosed sound fields using spherical wave functions.
• Accuracy of spherical wave function methods degrades with distance from the array.
• Limitations exist in extending reconstructions to the entire acoustic cavity.

Purpose of the Study:

• To extend accurate sound field reconstruction to the entire cavity.
• To compare the efficacy of a plane-wave basis with spherical wave functions in low-frequency sound fields.
• To analyze the impact of measurement noise, number of plane waves, and positions on reconstruction.

Main Methods:

• Utilized a plane-wave basis in the space domain for its non-decaying propagation characteristics.
• Compared the plane-wave method with the conventional spherical wave function method.
• Conducted simulations and experiments within a cylindrical cavity and an aircraft cabin mock-up.

Main Results:

• The plane-wave function method demonstrated superior reconstruction accuracy and data processing efficiency.
• Achieved entire sound field imaging with a single calculation, avoiding coefficient translations.
• Validated the method's effectiveness in an aircraft cabin mock-up.

Conclusions:

• The plane-wave basis method offers a more accurate and efficient approach to acoustic field reconstruction.
• This method enables global sound field imaging without complex coordinate transformations.
• Provides an alternative for recovering high-order spherical wave function coefficients in a global system.