annunciator

noun

1. an announcer.
2. a signaling apparatus, generally used in conjunction with a buzzer, that displays a visual indication when energized by electric current.

noun

1. a device that gives a visual indication as to which of a number of electric circuits has operated, such as an indicator in a hotel showing in which room a bell has been rung
2. a device giving an audible signal indicating the position of a train
3. a less common word for announcer