NUMERICAL AND EXPERIMENTAL STUDY OF A HYBRID ELECTRO- ACOUSTIC NONLINEAR SOUND ABSORBER IN A RESONANT ROOM

International audienceWe present a hybrid Electro-Acoustic Nonlinear Energy Sink (EA-NES) coupled to a resonant room. It is made of a baffled nonlinear membrane with its front face exposed to the noise in the room, and the rear face enclosed. The enclosure includes a feedback loop associating a microphone and a loudspeaker that control the acoustic pressure applied to the rear face of the membrane. The EA-NES action is based on the concept of Targeted Energy Transfer resulting from the nonlinear coupling between the absorber and an acoustic mode in the room (primary system). The nonlinear dynamics of the system is studied theoretically. The asymptotic study shows the possible existence of relaxation oscillations, which can be tuned by the control loop settings. The experimental study confirms theoretical predictions and shows that a hybrid EA-NES can reduce the sound level in a concrete building. Harmonic regime and Strongly Modulated Regime (SMR) are observed. The SMR responses are simulated with a good agreement