Two days in a row, after turning off engine, parked, this long tone at 1.1947 kHz appeared and then faded away: https://clyp.it/xedrwsuh I just happened to be recording and caught it on the 2nd day. I've heard it in the past, but rarely, and assumed it was another car's brakes, etc.
Then turned the engine back on, and two short whistles happened at similar frequencies, but jumping from lower to higher: https://clyp.it/jkycuejh
I couldn't tell where it was coming from. Sounded like it was coming from all directions or outside the car, but I heard it in two completely different locations on consecutive days after turning off the engine.
2016 Toyota Corolla LE