Calculus's deafness is a frequent source of humour in his interactions with other people, as he often repeats back what he thinks he has heard, usually in the most unlikely words possible. Additionally, he often diverts the subject of a conversation by responding to a misinterpreted remark. For example, "But I never knew you had...." leads Calculus to respond, "No, young man, I am not mad!" In the same book he believes that Tintin and Haddock are talking about his sister, before remembering a few moments later that he does not have a sister. He is not perturbed by his handicap, even if it is a source of deep frustration to his friends. He himself does not admit to being near-deaf and insists that he is "only a little hard of hearing in one ear."