Visiting Bangkok, Thailand, my father slipped off a curb and broke his wrist. It seemed to him that a fall in an exotic location deserved a better story than mere carelessness. He tried to make something up about falling off an elephant, but never learned to tell it with a straight face. Beethoven must have had similar thoughts about his deafness; the story about gradual loss of hearing lacked entertainment value.
Beethoven told visiting English pianist Charles Neate that he had been working on an opera–not Fidelio–and had to deal with mean-tempered tenor. The tenor had already rejected two arias on a particular text, but appeared to be satisfied with the third one. Glad to be rid of him, Beethoven went back to work on other passages he had to set aside to please the tenor. Unfortunately, not half an hour later, the tenor knocked on his door again. According to what Beethoven told Neate, he flew into such a rage as the man entered the room that he threw himself on the floor. When he got up, he was totally deaf.
On another occasion, he told Ignaz Schuppanzig that he had caught his deafness. He always sketched outdoors. One day it started to rain, but he was so enrapt in his work that he didn’t notice until the paper became too wet to write on. From that time on, he was incurably deaf.
It appears that Beethoven managed to tell these stories with a straight face. Neate and Schuppanzig passed them on to others. The anecdotes appear in all seriousness in Alexander Thayer’s notes for his biography of Beethoven and the diary of George Smart.