Beethoven was the first composer to include a chorus in a symphony, which became known as the ''Chloral'' Symphony Number 9. His piano music was the first to require the pianist to play the trill and the melody with one hand, as in the “Hammerklavier” Sonata.
Beethoven's compositional career is usually divided into Early, Middle, and Late periods. His early period started at the beginning of his career until about 1802. The middle period from about 1803 to about 1814, and the late period from about 1815 to 1826. In his Early period, Beethoven's work was strongly influenced by his predecessors Haydn and Mozart, but he also explored new directions and gradually expanded the scope of his work. His Middle (Heroic) period began shortly after Beethoven's personal crisis brought on by the knowledge of his increasing deafness. This period is noted for large-scale works that express heroism and struggle. Works from the Late period are characterized by their intellectual depth, formal innovations, and their highly personal expression. String quartets from this period were described as 'indecipherable' by Louis Spohr.
Around 1796, Beethoven began to lose his hearing. He suffered a severe form of tinnitus, a "ringing" in his ears. The cause of Beethoven's deafness is unknown, but it has been linked to evidence of lead poisoning. Beethoven used a special rod attached to the soundboard on a piano that he could bite. The vibrations would then transfer from the piano to his jaw to increase his perception of the sound. A large collection of his hearing aids such as special ear horns can be viewed at the Beethoven House Museum in Bonn, Germany.
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