Electroacoustic transducers, including micro-electro-mechanical systems (MEMS) microphones and speakers, whether electrostatic or piezoelectric, often exhibit resonances in their moving components, resulting in non-flat frequency responses, which are undesirable in many applications. This study investigates the damping mechanisms in such transducers, focusing on configurations in which the moving component has the form of a circular membrane or plate. A damping system consisting of a circular air gap between the moving component and a fixed wall with a central hole connecting to a backing cavity was analyzed. An analytical model was developed to calculate the displacement of the moving component and the acoustic pressure distribution within the transducer, treating both the membrane and plate configurations. The model incorporates the strong coupling between the displacement of the moving component and the acoustic pressure in the air gap, as well as the damping effects of thermoviscous boundary layers within the transducer. Analytical predictions for displacement, acoustic pressure, and mean displacement as functions of frequency were validated against numerical simulations. Excellent agreement was observed, confirming the model’s accuracy and highlighting its potential for optimizing the design of miniaturized transducers with improved frequency response characteristics.
Honzík et al. (Mon,) studied this question.