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…
Source: Gizmodo – How Lucasfilm Made The Last Jedi’s Leia Hologram Sound Authentically Crummy