Back at school this music teacher told us a story about Beethoven that I have ever since considered to be true but I have just realised that I have never heard it anywhere else. So my question is if there is any truth to it:
At a time when his deafness was progressing but he was not yet fully deaf, Beethoven was playing a signature piece of his. At the end of the concert, he could not hear anybody clapping, so he thought - “what is going on, have I gone completely deaf, or have I just lost the audience?”
He turns around to look at the audience to discover that he was not hearing them clapping because everyone was crying.
This sounds like a mild conflation of the story behind the premier of Beethoven's 9th Symphony. By that time, he was completely deaf, and so couldn't really keep the timing correct while conducting. But it was the premier, and the audience expected him to conduct his own symphony. So they actually had two stages, one that the audience watched, with Beethoven furious thrashing away at the air with the baton, and then a second conductor who was actually keeping time, and who the musicians were watching instead.
Unfortunately, the 9th is a very long symphony, and by the time the last movement was over, Beethoven's internal timing was lagging behind reality by quite a bit. So the symphony ended and the audience burst to their feet in applause, but Beehoven was still thrashing away silently at what he thought was the finale. The second conductor (in some stories it's the concert master) had to gently walk up and stop him, and turn him around so that he could see the audience's reaction.