^ I mean we all know what he was doing, but yeah, on its face this was just absolutely ridiculous and unnecessary. Especially when there were 2 stormtroopers right fuckin there.
Wonder if the Stormtroopers were – um, sir? We’re actually here… hello? Sure you don’t need help? okay, just asking…
And now we go to this scene, where we actually get a very different side of Kylo Ren. Where we see how unlike Vader he is. How tempestuous he is. How uncontrolled he is. […] We were really throwing sparks his way. I think the moment I actually just fell in love with Adam Driver was in his timing of this line. “Anything else?” This is the moment of course where Kylo Ren learns about Rey. And now, these two disparate pieces come together. — J.J. Abrams’ commentary on Star Wars: The Force Awakens.
“I was able to work with Adam Driver really directly and build the process for how his voice was going to sound in that mask. We built [it] in sound design and actually took it to Adam and got him to play with it. He could hear the process of his voice through the mask as he was doing it live, so we could use it like an instrument and play on it. So you could get these really creepy performances of him playing a very intimate recording right up on the mic. And yet it has this distorted, otherworldly feel through the mask, so it still keeps [dialog] intelligible. That mask’s sole function is to intimidate. It’s not keeping him alive like it [was for] Darth Vader; it’s just a mask of intimidation. We really wanted to work with that.
And Adam was so into working with us. At one point, we had to record when Adam was rehearsing for a play in New York. We set up across the street in a hotel across from his rehearsal space. And so he’d run over to us, and we’d work in a hotel room. We outfitted the closet in the hotel room as a makeshift recording room. So he’d come in and we’d work on it, [and] we’d send the files back to J.J. to see what he thought. That was some guerilla sound design, and Adam was really up for it. In fact now, whenever Adam has to do anything Kylo Ren, he demands me to be there, so [I’m] kind of his personal Kylo Ren recordist now. [laughs]”
– Matthew Wood, TFA supervising sound designer (interview published on Daily Dot, 2016/02/04)
Reylo Source 