Ravel composed his Vocalise for voice with piano. The unusual melodies and chord progressions make it a fascinating piece to hear. The piece was commisioned by vocal instructor of the Paris Conservatory, Amédée-Landely Hettich in 1907.
It is available in Ab major (the original key) and in Bb major, as arranged by Théodore Doney for multiple instruments and piano accompaniment.