Low-frequency perfect sound absorption achieved by a modulus-near-zero metamaterial

Area of Science:

• Acoustics
• Materials Science
• Metamaterials

Background:

• Acoustic metamaterials offer unique sound manipulation capabilities.
• Achieving high absorption at low frequencies with thin structures remains a challenge.

Purpose of the Study:

• To propose and demonstrate a mechanism for perfect absorption using modulus-near-zero (MNZ) metamaterials.
• To design an ultrathin acoustic metamaterial for efficient low-frequency sound absorption.

Main Methods:

• Analytical modeling of modulus-near-zero metamaterials with a focus on destructive interference.
• Numerical simulations to design and analyze an ultrathin acoustic metamaterial.
• Experimental validation using impedance tube measurements.

Main Results:

• A perfect absorber was analytically proposed based on destructive interference in MNZ metamaterials.
• An ultrathin acoustic metamaterial exhibiting monopolar resonance at 157 Hz was designed.
• Experimental results showed excellent agreement with analytical and simulated predictions, achieving >99% absorption.

Conclusions:

• The study presents a feasible approach for achieving perfect absorption at low frequencies using deep-wavelength metamaterials.
• The tunable nature of the effective modulus allows for precise control over absorption.
• This work has significant potential for practical engineering applications in noise control.