Low-frequency multi-order acoustic absorber based on spiral metasurface

Area of Science:

• Acoustics
• Materials Science
• Metamaterials

Background:

• Low-frequency sound absorption remains a challenge for traditional acoustic materials.
• Metasurfaces offer novel ways to manipulate sound waves for enhanced acoustic performance.

Purpose of the Study:

• To propose and experimentally validate a spiral metasurface for multi-order low-frequency sound absorption.
• To demonstrate flexible tuning of absorption orders with a constant external shape.
• To investigate the design parameters for optimized multi-order absorption.

Main Methods:

• Designing a spiral metasurface with tunable sub-cavities and recessed necks.
• Utilizing impedance manipulation principles for sound wave control.
• Fabricating samples using 3D printing technology for experimental verification.
• Conducting acoustic measurements to validate theoretical predictions.

Main Results:

• Achieved quasi-perfect sound absorption (>0.95) at multiple low-frequency orders.
• Demonstrated flexible tuning of each absorption order by modulating sub-cavities and necks.
• Obtained high-absorption metasurfaces with dual, tri, and four-chamber designs.
• Achieved a high ratio of lowest resonant wavelength to thickness (up to 78).

Conclusions:

• The proposed spiral metasurface effectively achieves multi-order sound absorption in the low-frequency range.
• The design offers flexible tuning and potential for broadband absorption with ultra-thin profiles.
• This technology has significant potential for noise reduction applications.