Early on in Star Wars: The Last Jedi, R2-D2 tries to get his disillusioned former master Luke Skywalker to join the fight against the First Order with what Luke calls a “cheap trick”—replaying the hologram that started Luke’s journey in the first place. But it turns out, a lot of work went into making that hologram sound like it had been accumulating dust since A New Hope.
Speaking to The Hollywood Reporter, Lucasfilm’s supervising sound editor Matthew Wood—nominated at this year’s Oscars for The Last Jedi—revealed that while the clip of Carrie Fisher herself was from the original tape recording Lucasfilm’s archives, the team took a decidedly analog approach to making it look dated and worn down.
In order to make Leia’s speech feel like it’s decayed a bit from sitting around in R2's memory for over 30 years, the team re-recorded a new copy of the message on an actual tape... and then beat the crap out of it:
Then, rather than doing a digital process on it, we recorded it to an analog piece of tape — people might not know what that is anymore — but we recorded it on that piece of tape a bunch of times then dragged it through the dirt at Skywalker Ranch. We crumpled it, crushed it, threw it in a lake, rubbed rocks on it, distressed it and tied it to a car and drove it around.
A few crumplings later, and you have one authentically old-sounding piece of dialogue ready to be fitted into a similarly-old-looking hologram. Sometimes the easiest moviemaking tricks work best!