Piezoelectric sensors in theaters and concert halls harness sound wave energy to create electricity

https://publishing.aip.org/publications/latest-content/putting-sound-waves-to-work-to-create-safer-public-spaces/

"proof of concept included 1,042 sensors powering 48 LED lights... mitigates hearing damaging noise above 70 dB... installed in walls, floors, and ceilings... system output switched between battery and direct harnessed output... variables include voltage needed to power main device component, frequency and intensity of the input sound, and piezoelectric sensors tested in parallel and serial configurations... smart power management, easily biodegradable and recyclable silica”

Related: Piezo Composites with Carbon Fibers for Motion Sensors
https://www.tohoku.ac.jp/en/press/piezo_composites_with_carbon_fibers_for_motion_sensors.html