This's a Skywalker Sound vocal effect used in the works of Ben Burtt. There's no connection to the WILHELM SCREAM here.
- Manassas: End of Innocence (2002)
- Indiana Jones and the Last Crusade (1989)
- Star Wars: Episode VI - Return of the Jedi (1983)
A good reference before sampling the vocal is in "The Last Crusade" during a shootout in the desert (following two explosions with Wilhelm screams). Sounds like "AAHuh!"