Integrated piezoelectric MEMS loudspeakers for in-ear applications
Résumé
This contribution introduces a MEMS-based in-ear headphone system. The core element is a chip loudspeaker manufactured solely using standard MEMS technology. It features multiple piezoelectrically driven bending actuators, which are mechanically decoupled from each other and are directly used for sound generation. In combination with an in-ear housing and dedicated driving electronics, the MEMS loudspeakers enable good performance at small device size. In an IEC 60318-4 ear simulator, for example, sound pressure levels of up to 110 dB are achieved across the entire audible frequency range. In addition, the headphones feature a high electroacoustic sensitivity of about 120 dB/mW, low harmonic distortion and a reproduction range significantly exceeding the audible range. The contribution covers the technology as well as a comprehensive electroacoustic analysis. In addition, the huge development potential concerning future loudspeaker generations will be discussed.