Trivia: Whenever Deckard occupies his room there is a low/high hum if you listen very carefully! This sound is very like or if not the very same low hum that can be heard on the Nostromo in the first Alien movie (1979). (00:31:30)
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Suggested correction: I'd always assumed it was from Alien, too, but years later I discovered that sound effect actually came from The Empire Strikes Back! Specifically when Luke is searching for Darth Vader in the dark corridors underneath Cloud City near the climax.
