This is the finding of researchers from the universities of Amsterdam and Maastricht, published in the British Medical Journal, who analysed the composer’s works through his lifetime.
It is known that Beethoven gradually became deaf over a number of years, and this is reflected in the way he wrote music.
Researchers found that there are three main stages of changes in his compositions. When he first started experiencing hearing loss between 1798 and 1800 and it worsening from 1806, the number of high notes (above 1,586Hz) in his music dropped from eight per cent to five per cent.
By the time he was writing his later string quartets in 1809-11, the frequency of high notes was just two per cent.
Interestingly, once Beethoven was completely deaf from 1824, his music again began to feature high notes, at about four per cent.
The Daily Telegraph reported that by 1805, Beethoven had reported difficulty in hearing woodwind instruments and by the time he was composing opus 74 and 95, he was placing cotton wool in his ears because of a buzzing noise.
By 1825 he could not hear his own Ninth Symphony.
Lead researcher Edoardo Saccenti suggested that the composer used lower-frequency notes so that he could hear the music better when it was performed.
“When he came to rely completely on his inner ear he was no longer compelled to produce music he could actually hear when performed and slowly returned to his inner musical world and earlier composing experiences,” he added.
However, Mr Saccenti stressed that as the study only looked at a small number of Beethoven’s compositions, the results are not entirely conclusive. This, he said, would require “exhaustive statistical and spectral analyses of the composer’s complete catalogue”.