Active Acoustic Resonators with Reconfigurable Resonance Frequency, Absorption, and Bandwidth

This study demonstrates the relevance of active electroacoustic resonators to controlling the performance of subwavelength inclusions in an acoustic metamaterial, which is a major difficulty. A feedback control scheme for loudspeakers (used as acoustic scatterers) is proposed, involving passband-current control via real-time sensing and processing of the pressure signal by a field-programmable gate array. This allows external, independent tuning of the absorption (including levels near zero and near unity), bandwidth, and resonance frequency of subwavelength acoustic resonators. The work offers a viable way past the current limitations of metamaterials, to enable practical applications.