Midway through Solaris (2002), during an argument about whether she's real or not, Phi Creature Rheya says "my voice sounds the way it does because that's how you remember it." The real Rheya (depicted in flashbacks) spoke with a distinctly different voice than the Phi Creature.
Spoiler alert:
>!When Rheya speaks to Kelvin in the final scene (after the station was consumed by Solaris,) she speaks with the same accent as the real Rheya did. Thus we know the lovers are finally reunited (presumably, in the afterlife) - and Death shall have no dominion.!<