Direct discrete complex image method for sound field evaluation above a non-locally reacting layer

Area of Science:

• Acoustics
• Materials Science

Background:

• Thin porous layers are crucial for sound absorption and noise control.
• Predicting sound fields above low flow resistivity porous media is challenging due to complex reflection coefficient behavior.

Purpose of the Study:

• To introduce a novel framework for analyzing the sound field above rigid-backed, non-locally reacting porous samples.
• To overcome computational challenges associated with singularities and branch points in reflection coefficient expressions.

Main Methods:

• Utilizing the direct discrete complex image method.
• Approximating the reflection coefficient directly using complex exponentials via the matrix pencil method, avoiding quasi-static term extraction.

Main Results:

• Efficient and accurate sound field computation in both near- and far-fields for melamine and rockwool samples.
• Predicted specific impedances show good agreement with experimental in situ measurements.

Conclusions:

• The proposed framework provides an efficient and accurate method for sound field prediction above porous media.
• The framework has potential applications in object detection and sound propagation modeling in layered media.