"EBS?"
Emergency Broadcast System. A series of squawks and electronic noises that precedes the takeover of signal from radio and television, followed by either an actual emergency alert, or "this is only a test." It dates back to the bad old "duck and cover" days of the Cold War. If it's being "tested" very frequently, some get a little freaked, under the assumption that there is an unspoken reason for the activity.
Carolyn