Mark Henderson answered
Beethoven composed music in his head. His deafness made relatively little impact upon his composing, and in fact some of his most famous works were composed when he was either partially or completely deaf.
With a trained musical mind such as Beethoven's, it is not necessary to hear the music to know what you are writing. He could imagine the sounds of every orchestral instrument and their notes in his head and therefore did not need an orchestra in order to write his compositions.
Both Mozart and Britten also composed their pieces in this way, and they weren't even deaf! Indeed, Beethoven never considered his deafness an obstacle to his writing ability.
- By 1798 Beethoven was suffering from the onset of deafness
- By 1801 he had lost 60% of his hearing.
- He was completely deaf by 1816.
- Symphony No.9 in D minor (one of his greatest works) was composed between 1817-24.
How Beethoven coped with deafness.
Despite not being able to hear instruments, Beethoven could feel their vibrations, so he cut the legs off his piano and laid it on the floor - reasoning that he could feel the notes even if he could not hear them.
Beethoven also devised a method using a wooden stick (connected to a piano) which he would put in his mouth - and this made it easier for him to feel the vibrations in his head.
He stopped performing music in 1811, and found social situations increasingly difficult, but never gave up composing.