Reverberation Time Control by Acoustic Metamaterials in a Small Room

TL;DR

This paper presents a novel design of acoustic metamaterials with multiple subwavelength resonators to control reverberation time in small rooms, achieving broadband absorption and uniform sound quality.

Contribution

It introduces a reverse-engineering approach to design acoustic metamaterials tailored for specific acoustic environments in small spaces.

Findings

Experimental results align with numerical predictions.

Design achieves broadband absorption across targeted frequencies.

Applicable to various small room acoustic scenarios.

Abstract

In recent years, metamaterials have gained considerable attention as a promising material technology due to their unique properties and customizable design, distinguishing them from traditional materials. This article delves into the value of acoustic metamaterials in room acoustics, particularly in small room acoustics that poses specific challenges due to their significant cavity resonant nature. Small rooms usually exhibit an inhomogeneous frequency response spectrum, requiring higher wall absorption with specific spectrum to achieve a uniform acoustic environment, i.e., a constant reverberation time over a wide audible frequency band. To tackle this issue, we developed a design that simultaneously incorporates numerous subwavelength acoustic resonators at different frequencies to achieve customized broadband absorption for the walls of a specific example room. The on-site experimental measurements agree well with the numerical predictions, attesting to the robustness of the design and method. The proposed method of reverse-engineering metamaterials by targeting specific acoustic requirements has broad applicability and unique advantages in small confined spaces with high acoustic requirements, such as recording studios, listening rooms, and car cabins.