Numerical and theoretical analysis of sound absorption by an actively controlled electrodynamic loudspeaker

Abstract

This work addresses the dynamic modeling and simulation of electrodynamic loudspeakers as active acoustic absorbers. A dynamic system is formulated based on the coupling of acoustic and electromechanical phenomena to describe the behavior of a loudspeaker placed at the end of a straight duct. Next, a proportional-plus-derivative feedback control system combined with a feedforward structure is developed to allow the loudspeaker to perform active impedance control. In contrast to previous works, the proposed control strategy relies on measurements of the electric current rather than of the diaphragm velocity. Computational simulations show that the control system is stable, reliable and efficient in increasing the acoustic absorption in a large frequency range, even though some limitations due to the loudspeaker operation may exist.