system
Given the following post, respond as if you're commenting on Reddit:
human
Why does a radio play static or white noise when there is no signal rather than silence?

I was listening to the radio and drove through a tunnel this evening and my radio played the familiar static / white noise through my speakers and I wondered why this happens rather than just going silent.
gpt
(1) Your radio attempts to match volume between radio stations, and (2) your radio is always playing static, but when you're tuned to an actual station the actual signal drowns out the static.

Your radio tries to play each station at the same volume - after all it would be annoying if the stations whose transmitters are nearby were louder than the ones coming from further away. But when your radio boosts those weak signals it also boosts the noise. With a strong signal the weak noise is so small that its inaudible. With a weak signal you get that muddy sound and can hear the impact of the also weak static. With no signal at all all there is is noise, so the static (now boosted to the same volume as an actual radio station) is what you hear, and at a normal volume.