Sergei Rachmaninoff (1873-1943) wrote the Vocalise in 1915, as the last of 14 Romances. It's a song without lyrics. Instead only one vowel is sung, mostly the 'ah'-sound. It's one of Rachmaninoffs more popular pieces, which has been arranged by many performers for different instruments, ranging from versions for violin and piano to a full orchestra (even a version for theremin is known to exist...
