Experimental assessment of low-frequency electroacoustic absorbers for room modal equalization in actual listening rooms

In listening rooms, low-frequency modal resonances lead to uneven distributions in space and frequency of the acoustic energy, as well as an alteration of the temporal behavior of the original music content. While usual absorption techniques have severe limitations for reducing the negative impact of room modes, the authors have previously proposed the use of electroacoustic absorbers for room modal equalization. This device consists of a current-driven, closed-box loudspeaker associated to a hybrid sensor-/shunt-based impedance control. In this communication we assess the performance of these electroacoustic absorbers in actual listening rooms, by measuring frequency responses at different locations, as well as their modal decay times. The electroacoustic absorbers perform as expected and the room modal equalization is clearly improved in the low-frequency range.