https://www.nytimes.com/1983/07/10/arts/music-view-did-shostakovich-have-a-secret.html

Shostakovich may have carried a piece of German shrapnel around in his brain for the last 34 years of his life and used it to help him compose music…Shostakovich, however, was reluctant to have the metal removed and no wonder: “Since the fragment had been there, he said, each time he leaned his head to one side he could hear music. His head was filled with melodies – different each time – which he then made use of when composing. Moving his head back level immediately stopped the music.”