Effect of the temperature on the impedance control of pressure-based, current-driven electroacoustic absorbers: Addressing the loss of passivity using a viscoelastic material model

In active noise control, pressure-based control strategies for electroacoustic absorbers depend on the loudspeakers’ electromechanical properties, known as Thiele–Small parameters, to implement impedance control. Due to the viscoelastic nature of loudspeaker materials, these parameters are sensitive to environmental conditions, particularly temperature. This study investigates the impact of temperature on the impedance control of electroacoustic absorbers. The acoustic impedance of several absorbers is measured over a broad temperature range, and an analytical model is used to identify the variation of the Thiele–Small parameters with temperature. A viscoelastic material characterization framework is then proposed, employing the Fractional Zener, Generalized Maxwell, and Generalized Fractional Maxwell models. These models are identified for individual absorbers and compared in terms of accuracy and computational cost. A generalized approach through a normalized curve derived from multiple absorbers is introduced to estimate the parameters of unknown absorbers. The pressure-based control law is subsequently updated to include temperature-dependent parameters, enabling evaluation of their influence on absorber passivity. Results demonstrate that adapting the control strategy using either direct measurements or model-based estimations enhances the acoustic passivity of electroacoustic absorbers.