All that follows is silence though, as Seth's natural response is to sign in response to cue them in that he was mute. Also pictures? What was he talking about? Being such a recluse though Seth had likely heard Luka's music on the radio and such, he's never seen any pictures of the artists that play the songs he's listened to.

So Seth ends up just being very, very confused when there's no response to his signing from the other, not knowing they were blind.