Acoustic Metameterial with Negative Modulus

TL;DR

This paper reports on an acoustic metamaterial that demonstrates negative effective modulus in the low-frequency range, with experimental validation and theoretical explanation of its frequency-dependent behavior.

Contribution

It introduces a novel one-dimensional acoustic metamaterial with negative modulus, supported by experimental data and a theoretical model.

Findings

Negative effective modulus observed below 450 Hz

Sound propagation above 450 Hz remains unaffected

The frequency response resembles plasma oscillation in metals

Abstract

We present experimental and theoretical results on an acoustic metamaterial that exhibits negative effective modulus in a frequency range from 0 to 450 Hz. One-dimensional acoustic metamaterial with an array of side holes on a tube was fabricated. We observed that acoustic waves above 450 Hz propagated well in this structure, but no sound below 450 Hz passed through. The frequency characteristics of the metamaterial has the same form as that of the permittivity in metals due to the plasma oscillation. We also provide a theory to explain the experimental results.