Beethoven's going deaf affected his musical output, because it was difficult to play. He couldn't hear the audience nor the orchestra. He failed to perform his Piano ConcertoNo. 5. When he performed his Ninth Symphony in 1824, he needed the conductor to give him cues. Beethoven had special hearing aids. Between 1815 and 1817, his output dropped again. Regardless of his condition, Beethoven produced many pieces of music.