A slide whistle falling from a hopeful note to a resigned one, with a slow wobble on the way down. Use it for characters dropping out of frame, plans collapsing, stock prices, and any moment that deserves the oldest joke in animation.
sine sweeping 1150 Hz -> 210 Hz over 0.75 s, on an exponential curve wobble: 7 Hz vibrato, depth shrinking from ±4% to ±1% envelope: 40 ms attack, held flat to 0.6 s (the whistle is blown and held), then a 180 ms release no soft clip: the sine is clean, the wobble supplies the breath