MEMS Acoustical Actuators: Principles, Challenges and Perspectives

10 years ago, the MEMS technology unexpectedly revolutionized the global microphone market. Will the MEMS technology have similar impact on the loudspeaker market? This article introduces MEMS loudspeakers. It covers the underlying manufacturing technology as well as technical requirements for the headphone and hearing aid market. It covers a section about artificial ear measurements for MEMS loudspeakers. Moreover, the article underlines the importance to use digital signal processing to increase MEMS performance and sound optimization. A section summarizes six different MEMS loudspeaker approaches from the literature. The descriptions contain technical specifications and the mechanical principle of sound reproduction. Finally, the article considers aspects of acoustics in very small systems. Here, thermoviscous boundary layer effects dominate acoustics.