DAVID ACORD: “I think the most obvious new sound effect in the movie is Kylo’s lightsaber. We were attempting, along with his Force power effect, to create sound effects that would mimic his persona, which is this raw power he has that’s not quite formed. He’s not well trained, but he’s extremely powerful. It’s a little wild and dangerous. The sword itself, the look of the sword has the extra darts coming out the side, and it’s really sparky and wavery and it looks a little homemade. The idea of the sound was to match that–something that sounds like raw energy, just pure power, very brutal and kind of wild and dangerous sounding.
The Force sound to go along with Kylo had that deep, raw, animalistic sound. It’s a chunky, raw growl that’s supposed to imitate the Force power he wields, which is a little more raw versus Rey’s Force power , which tends to be—in the few moments when she’s using the Force, hers is a little more smooth and rhythmic and like a heartbeat. That’s the contrast between the two.”
[from KYLO REN, BB-8, AND MORE WITH THE SOUND DESIGNERS OF THE FORCE AWAKENS]