Acoustic Validation of Electrostatic All-Silicon MEMS-Speakers

MEMS based acoustic transducers are of high interest for in-ear-applications such as hearables and hearing aids. In this paper we present detailed measurements of CMOS compatible MEMS speakers based on electrostatic bending actuators. The results are discussed in the context of basic modeling approaches and analytical calculations. At 500 Hz a sound pressure level of 70 dB was measured with a THD of 5% in a standard ear simulator. The THD is dominated by second-order harmonic distortion products. Future work will focus on increased SPL and reduced distortion with optimized actuator design.