THIN PIEZO ELECTRONIC BUZZER 3-12VDC

Thin Enclosed Piezo Electronic Buzzer 3-12VDC Knock Sensor Alarm

Rated Voltage (Square Wave): 12Vp-p
Operating Voltage: 1-30Vp-p
Rated Current (MAX): 3.5mA
Min. Sound Output at ten cm: 85db
Resonant Frequency: 1300Hz ± 500 / 4000HZ ± 500
Operating Temperature: -20 ~ +60
This large (30mm diameter) piezo element is nicely enclosed with mounting holes so you can attach easily. Piezo elements convert vibration to voltage or voltage to vibration. That means you can use this as a buzzer for making beeps, tones and alerts AND you can use it as a sensor, to detect fast movements like knocks. You can also use it under a drum pad to make a drum/crash sensor

It's rated for up to 12Vpp use but you can also use 3 or 5V square waves and its plenty loud.

https://www.arduino.cc/en/Tutorial/ToneMelody?from=Tutorial.Tone

https://www.arduino.cc/en/Tutorial/Knock