Sounds at a fireworks show

OOHS

Listen closely for the crowd’s spontaneous gasps when the sky lights up in color.

This clue plays on the sounds people naturally make when watching fireworks. "Oohs" (along with "aahs") are the spontaneous exclamations of wonder you hear during a display, so the answer captures that familiar reaction. It’s a straightforward example of a clue where the answer is a sound rather than a word with a complex definition. Think of the last time you saw fireworks—the crowd probably said this without even realizing it.