People in radio station studios generally don't listen to the over-the-air signal because there is a delay. A silence sense is a circuit that monitors the over-the-air signal and takes action when it's been too quiet for too long. This is usually an indication that something has failed, either at the transmitter, or in the studio-transmitter link. It is sometimes triggered by dramatic pauses in classical music and talk show content, but in those cases is ignored by the DJ/host/producer.
They've been around forever, and can be made from simple analog circuits. In the stations where I've worked, if the silence sense activated, a red light lit up in the DJ booth, and the engineering department. Some stations had a secondary silence sense that would wait a bit longer, and light up a light bulb at the receptionist's desk because she had the master list of phone numbers to call the right people in case of a transmission failure.
There are thousands of radio station transmitters that are far enough away from the originating studio that it's not possible for the studio to hear the over-the-air signal, so a silence sense on top of a mountain, next to the transmitter could send an alert packet via this satellite service back to the studio to let someone know something is wrong.
https://www.insideradio.com/free/fcc-slaps-birach-broadcasti...
