On a visit to the library I happened to notice a man and a woman, both deaf, signing with intense gestures, apparently in a heated debate.
The man said something, and the woman seemed upset. She started signing her reply very fast, to the point where the man couldn't understand a word; she also signed in big, wide gestures, which is the equivalent of volume.
Finally, looking strained, her companion took her hands, "silencing" her. The he signed, very small and slowly, "You don't have to shout, I'm not blind."