Conversation so far:
is emmett in season 5 of switched at birth
Sean Berdy appears in season 5 of Switched at Birth as Emmett Bledsoe.
is sean berdy deaf
Sean Berdy was born deaf.
does sean berdy know american sign language
Sean Berdy's first language is American Sign Language.

Question: how many users are there
Self-contained rewrite: how many american sign language users are there