Hollywood film director Sam Raimi is at Mobile World Congress today, giving a content creators perspective on the future of mobile entertainment. Sound, notes Raimi, is invisible, so we dont know what were missing when experiencing a film at home or on a mobile device instead of a fully outfitted theater. Describing the ability of sound to convey emotion at a subliminal level, he asks the audience, when was the last time you cried at something that was presented on a mobile device?