One of this year’s major cultural anniversaries has been the centenary of the death of Debussy, a composer who ranks alongside Schoenberg and Stravinsky as a herald of our modern sound-world. You could say that 20th-century music began in 1913 with Stravinsky’s Rite of Spring. But you could also pre-date its arrival to Debussy’s Prélude à l’après-midi d’un faune or his opera Pelléas et Mélisande, both from the 1890s. And as a rule-breaking way with the human voice drove Debussy’s development, his 100 or so songs made an appropriate theme for this year’s Oxford Lieder Festival – which is the most ambitious annual fixture of its kind in Britain, platforming conveyor belts of singers in recitals round the clock across two weeks.