Place it just after the mistake is shown, between Enemy Spotted and No God Please No, so the first sound sets up the threat, this clip marks the realisation, and the second sound carries the fallout.
关于此声音
This is a 1.2-second voice clip saying 'oh no' from Half-Life, a brief reaction to something going wrong in the game. It lands as comic dread, the moment of realising a mistake just before the consequences arrive, and it stays funny because the reaction is so brief and familiar to anyone who has watched a plan collapse in a game.