These're Skywalker Sound/Star Wars sound effects, created by Ben Burtt for the legs of the AT-AT walkers in Star Wars: Episode V - The Empire Strikes Back (1980).
According to a recent interview, "for “the metallic sounds of the squeaking joints,” Burtt didn’t have to go far, famously recording the squeaky lid from a dumpster in front of his home. “It’s the sound I’d hear when I’d throw the trash away,” he says, mimicking the noise of opening the lid."
Sound Effect Description
They're those "RAH!" trumpet-like roar sounds when an AT-AT moves its legs.
- 102 Dalmatians (2000) (Heard once in a very high pitch.)
- Indiana Jones and the Temple of Doom (1984)
- Metro (1997) (Heard once in a very high pitch.)
- Rogue One: A Star Wars Story (2016)
- Star Wars: Episode III - Revenge of the Sith (2005)
- Star Wars: Episode V - The Empire Strikes Back (1980) (debut)
- Star Wars: Episode VI - Return of the Jedi (1983)
- Terminator 3: Rise of the Machines (2003) (Heard once for a car skid.)
- Thomas and the Magic Railroad (2000)
- Toy Story 2 (1999) (Heard once in a very high pitch.)
(Higher-pitched version incorporated into an AT-AT sequence.)