In-Ear Headphone System with Piezoelectric MEMs Driver
This article presents a prototype in-ear headphone system based on a previously disclosed piezoelectric MEMS driver technology (piezoMEMS). The centerpiece of the earphone is a 4 mm x 4 mm piezoMEMS chip loudspeaker that on its own achieves broadband sound pressure levels of up to 110 dB in an IEC 60318-4 ear simulator. A specifically designed enclosure allows for easy installation of the piezoMEMS driver and takes first steps in optimizing the acoustic performance. Furthermore, the system comprises a specially tailored amplifier as well as a dedicated signal processing concept. The article describes the ideas behind the system, discusses the particular challenges in designing the piezoMEMS earphone, shows measurement results, and, finally, discusses the vast opportunities for future research.