Half-Space Sound Field Reconstruction Based on the Combination of the Helmholtz Equation Least-Squares Method and...

Area of Science:

• Acoustics
• Signal Processing
• Computational Physics

Background:

• Near-field acoustic holography (NAH) typically requires free sound fields.
• Reflective surfaces create non-free sound fields, hindering conventional NAH source identification.
• Vibrating objects above reflective ground pose challenges for accurate acoustic measurements.

Purpose of the Study:

• To develop novel half-space NAH techniques for reconstructing sound fields above a reflecting plane.
• To adapt the Helmholtz Equation Least-Squares (HELS) method for non-free sound field conditions.
• To enhance the accuracy and applicability of NAH in practical environments.

Main Methods:

• Developed two half-space NAH techniques based on the HELS method.
• Introduced the concept of equivalent sources within the HELS framework.
• Tested spherical wave and monopole equivalent sources to model reflected sound.

Main Results:

• Both developed techniques demonstrated higher reconstruction accuracy compared to the conventional HELS method.
• The methods successfully reconstruct sound fields in half-space environments.
• Neither technique requires knowledge of the reflecting plane's surface impedance.

Conclusions:

• The proposed equivalent source-based HELS methods effectively reconstruct sound fields above reflective surfaces.
• These techniques overcome limitations of conventional NAH in non-free sound fields.
• The study broadens the application range of HELS-based NAH for practical acoustic measurements.