Electroacoustic resonators: system identification and stability

An Electroacoustic Resonator consists of a loudspeaker used as a membrane resonator, through anacoustic pressure-based controlled electrical current, in order to vary its vibrating velocity in re-sponse to an exogenous sound field. This way, the loudspeaker membrane can be turned, for example,into an effectively broadband sound absorber. However, the effectiveness and stability conditions ofsuch an active device are intrinsically dependent on the accurate knowledge of its electromechanicalconstituents and the whole control chain, and any mismatch might impair significantly the controlperformance. In this paper, we propose a new method for identifying the Thiele-Small parametersof a loudspeaker to be used as an active electroacoustic resonator through a digitally-implementedcontrol architecture. Then, numerical and experimental investigation are undertaken to show how theapplication of Impedance Control laws affects the stability of the electro-mechano-acoustical system.An experimental verification of the acoustic performance of the proposed control strategy is provided,leading to concluding discussion on further developments.