Ward Swingle, who has died aged 87, first had the idea of singing the works of JS Bach to the scat syllables of jazz in the early 1960s, during a quiet moment as a backing singer for recordings in Paris. The American-born musician – he was also a fine pianist – had been introduced to that world by the French jazz vocalist Christiane Legrand. She subsequently became lead soprano for Les Swingle Singers, the first of his lineups to provide one of the most distinctive sounds in popular music.