The distributed mode loudspeaker (DML) technology is a flat panel loudspeaker from which sound is generated a set of electromechanical actuators fixed on the panel, inducing distributed vibratory modes within the panel. When used for sound diffusion, it has many advantages over traditional cone loudspeakers in terms of weight, size, and durability. However, it is generally considered as a poor sound radiator at low frequencies, and the usual frequency response is uneven and complex, strongly dependent on the modal response of the vibrating structure. Recently, the Acoustic Group of LTS2 has developed a concept of electroacoustic absorber, based on a feedback-controlled loudspeaker system, usable for damping the low-order modes in rooms.

This project intends to investigate active structural acoustic control (ASAC) strategies to use a DML panel as a low-frequency soundproofing disposal in a room, either by absorption or redirection of sound wave. The challenging task is to identify the control law to be assigned on each independent control unit (electromechanical actuator + sensor) embedded into the DML panel that will allow for an effective soundproofing.

The proposed work will mainly consist in:

• studying different control strategies with the help of FEM simulation software (COMSOL Multiphysics) and MATLAB,

• defining an optimal configuration/strategy with respect to desired soundproofing performance,

• achieving preliminary experimental assessments on a multi-actuated panel demonstrator.

Profile: Mechanical engineering

Context: Theory (30%), Design and modeling (50%), experiments (20%)