Dynamic piezoelectric MEMS-based acoustic attenuators

Abstract Noise-induced hearing loss is the most prevalent global occupational disease but can be prevented by using Hearing Protection Devices. Acoustic vents are crucial in the design of hearing protection devices, earphones, and hearing aids, serving to balance effective sound attenuation with natural sound perception and user comfort. A hybrid acousto-mechanical vent is presented here, facilitating controlled acoustic impedance using a Pb(Zr,Ti)O3-based thin film piezoelectric micromechanical system. A combination of mechanical stress-compensation and novel design techniques are used to achieve a distortion-free acoustic throughput with an impedance-range from 3.6 to 500 MΩ. At 30 V bias, the maximum power consumption is below 400 nW. It is shown that the system response can be well simulated using Lumped Parameter Modelling, accurately reflecting the measured dynamic attenuation range of close to 140. This highly reliable system, assessed using accelerated lifetime measurements, offers possibilities for developing smaller, lighter, and more energy-efficient hearing protection devices.