So much has been written about those few words at the end that Bob whispers into Charlottes’ ear. We can’t hear them. They seem meaningful for both of them. Coppola said she didn’t know. It wasn’t scripted. Advanced sound engineering has been used to produce a fuzzy enhancement. Harry Caul of The Conversation would be proud of it, but it’s entirely irrelevant. Those words weren’t for our ears. Coppola (1) didn’t write the dialog, (2) didn’t intentionally record the dialogue, and (3) was happy to release the movie that way, so we cannot hear. Why must we know? Do we need closure? This isn’t a closure kind of movie. We get all we need in simply knowing they share a moment private to them, and seeing that it contains something true before they part forever.
– Roger Ebert on Lost In Translation