The siren chirp is basically a priority siren played for like a millisecond when a trooper has a regular looped siren playing and it will only turn on if the trooper puts his car in park while the regular looped siren is playing. This feature is to help troopers relocate their car if they chase a suspect into the woods for example and have to go back to the patrol vehicle after the scene is deescalated. Hope this helps but also I need what that low frequency wail siren is called, It’s like a howler more than a rumbler if anyone knows please add a comment.