The EU project "Listen2Future" https://www.listen2future.eu investigates the potential of piezoelectric acoustic transducers to provide new solutions in the application areas of health & well-being and digital industry & energy.

One focus of this program is piezoelectric MEMS microphones, which are used for medical measurements and especially in hearing aids. Here, a wide dynamic range to record sounds at different volumes without distortion is an important target parameter. At the same time, acoustic resonances should be minimized, which are difficult to predict when designing a microphone due to its installation in a housing. In addition, microphones for hearing aids have to be very energy efficient to allow long operating times between recharging.

To address all of these challenges, a novel microphone driver that uses active feedback is being investigated at LSE. This means that parts of the output signal are fed back to the MEMS microphone to both damp resonances and counteract diaphragm displacements. This increases the dynamic range, allowing a more sensitive diaphragm with higher linearity."