Flat-panel loudspeaker simulation model with electromagnetic inertial exciters and enclosures

We present a lumped element equivalent model of a flat-panel loudspeaker including multiple bending modes of an elastic plate as well as the dynamical influence of affixed inertial exciters and an enclosure. The models presented here are analogous to classic loudspeaker design models-the main difference being that flat panel loudspeakers have many more degrees of freedom than conventional loudspeaker drivers. The panel's natural resonant frequencies are shifted by the dynamical coupling to the exciters and the enclosure, which are fundamental for predicting the audio response of various designs. We present a model of this coupled system and explore methods for obtaining practical results. Three important design aspects are illustrated through simulations: first, the effective low-frequency cutoff of the flat-panel speaker is determined by the higher of either the exciter resonant frequencies or the lowest panel resonant mode; second, rigidly backed exciters can be employed to avoid mode-splitting at low frequencies; and last, achieving resonances below 100 Hz with a panel mounted near a wall requires the use of panels with considerable mass. Measurements on prototype designs show close agreement with the model simulations.