Living in West Philadelphia as I do, near two large hospitals, I hear sirens of some sort every other night or so. Unless it’s a fire siren and it’s on my street, I tune them out; I learned the skill long ago. (I’ve seen plenty of cops and some ambulances turn on their sirens just long enough to get through an intersection, which helped train me to ignore them.)
Helicopters are much less common, but are usually headed to the hospital or to film a traffic jam; only if they stop and hover do I pay attention. The most memorable time a chopper parked overhead at night was about five years ago, when the steeple of a neighborhood church collapsed in the middle of the night. (No injuries–lucky/miraculous, as the church was doubling as a homeless shelter at the time. It was a Protestant church or I would have nicknamed it Our Lady of Deferred Maintenance.)
When I lived on 42nd Street I learned to ignore flashing lights as well; usually they were either traffic stops or tow trucks removing double-parked cars that blocked the trolley tracks. One night the lights flashed on and on and on right outside my window, and I eventually got curious and looked out to see what kind of traffic stop was taking so long. Surprise! The guys around the car were wearing DEA shirts.
42nd Street was also where I saw my first police chase–on foot; a uniformed cop was calling “Don’t run!” and running, well, jogging really, after a crying young woman who was running very slowly (too distraught to really get some speed on, I think). Never did learn what that was all about.
(There’s a distant siren right now. Can’t tell if it’s police or fire.)
I’ve only seen one police car chase, on a Sunday morning; at least two marked cars were following a young man in a dull black sedan down Walnut Street, not at a very high speed.