Intermittent whistling noise in Museum District/Med Center area?

I’m wondering if anyone can help me identify this sound. I live in the Museum District, and throughout the day I hear an intermittent 2-second whistle. The kind that decreases in pitch, like a firework going into the air. It’s faint, but it’s on and off all day. Is this a bird? Is someone sending up flares? Is my neighbor playing a whistling noise on a speaker specifically to drive me bonkers?