buzzer; personal alarm
Refers to any device that makes a buzzing sound, including doorbells, game-show buzzers, and personal safety alarms.
When walking at night, it's reassuring to carry a personal alarm.
On the quiz show, please press the buzzer when you know the answer.
Please press the buzzer at the reception desk.
The buzzer sounded to signal the end of the exam.
If you feel in danger, sound the emergency buzzer.