As early as 1801, Beethoven wrote to friends describing his symptoms and the difficulties they caused in both professional and social settings (although it is likely some of his close friends were already aware of the problems).[48] Beethoven, on the advice of his doctor, lived in the small Austrian town of Heiligenstadt, just outside Vienna, from April to October 1802 in an attempt to come to terms with his condition. There he wrote his Heiligenstadt Testament, a letter to his brothers which records his thoughts of suicide due to his growing deafness and records his resolution to continue living for and through his art.[49] Over time, his hearing loss became profound: there is a well-attested story that, at the end of the premiere of his Ninth Symphony, he had to be turned around to see the tumultuous applause of the audience; hearing nothing, he wept.[50] Beethoven's hearing loss did not prevent his composing music, but it made playing at concerts—a lucrative source of income—increasingly difficult. After a failed attempt in 1811 to perform his own Piano Concerto No. 5 (the "Emperor"), which was premiered by his student Carl Czerny, he never performed in public again.
A large collection of Beethoven's hearing aids, such as a special ear horn, can be viewed at the Beethoven House Museum in Bonn, Germany. Despite his obvious distress, Czerny remarked that Beethoven could still hear speech and music normally until 1812. By 1814 however, Beethoven was almost totally deaf, and when a group of visitors saw him play a loud arpeggio of thundering bass notes at his piano remarking, "Ist es nicht schön?" (Is it not beautiful?), they felt deep sympathy considering his courage and sense of humor (he lost the ability to hear higher frequencies first).
As a result of Beethoven's hearing loss, his conversation books are an unusually rich written resource. Used primarily in the last ten or so years of his life, his friends wrote in these books so that he could know what they were saying, and he then responded either orally or in the book. The books contain discussions about music and other matters, and give insights into Beethoven's thinking; they are a source for investigations into how he intended his music should be performed, and also his perception of his relationship to art. Out of a total of 400 conversation books, it has been suggested that 264 were destroyed (and others were altered) after Beethoven's death by Anton Schindler, who wished only an idealised biography of the composer to survive. (Wikipedia)