What is the device with the lowest sound pressure level and the lowest frequency among audio devices?

Buzzer. According to the query on the Pacific Science and Technology Network, the buzzer is an electronic sounder with an integrated structure. It is powered by DC voltage and is widely used in computers, printers, copiers, alarms, electronic toys, automotive electronic equipment, telephones, and timers. As a sound-generating device in electronic products, the buzzer is the device with the lowest sound pressure level and low frequency among audio devices.