Something I've wondered... when politicians give speeches they often have some hand gesturing from a sign language interpreter standing next to them. But I've never understood why this is better than subtitles. If you're deaf then wouldn't you rather read text than follow sign language?
There's more to speaking than just the words. Sign language can convey inflection and emotion in ways that closed captions cannot. Watch someone signing: they use their face and body to convey emotions like anger, confusion, hesitation, love, joy, and the rest of the human range.
And that's the "original" emotion, it's not filtered through another human being. When you watch a movie without audio and with subtitles (like in a bar or on a bus), the emotions of the speakers are already awfully clear from the visuals.