In the following site I found astonishing information about a performance of Björk singing Schoenberg’s Pierrot lunaire. http://lostsongs.bjorkish.net/pierrotlunaire/

Björk  said in an interview to the New Yorker on 23 August 2004: “It was an amazing experience for me,” she recalled. “The songs left so much to the imagination of the singer—you know, they were originally written for a cabaret singer or an untrained singer like me. Kent Nagano wanted to make a recording of it, but I really felt that I would be invading the territory of people who sing this for a lifetime.” As a person who wrote one or two things about Pierrot lunaire and especially about the performance of Sprechstimme I would like to suggest that it is a pity that she didn’t record the piece in a commercial recording. This would do good to Schoenberg to Pierrot and to her. I hope she will change her mind.