Theatre of Voices

After Hillier's move to Copenhagen in 2003, membership in the group became more international, with members drawn from Denmark, Poland, England, and the United States.

Together Hillier and Theatre of Voices have enjoyed close collaborations with numerous composers and instrumental ensembles: Arvo Pärt, Steve Reich, Terry Riley, John Cage, the Kronos Quartet, Ingram Marshall, John Adams, Karlheinz Stockhausen, Pelle Gudmundsen-Holmgreen, London Sinfonietta, Michala Petri, Jóhann Jóhannsson, Fretwork, Phantasm, Concerto Copenhagen, Kaija Saariaho, Peter Sellars, David Lang, Michael Gordon, Pablo Ortiz, Heiner Goebbels, the Smith Quartet, Meta4 String Quartet, Helena Tulve, Sunleif Rasmussen, John Luther Adams, and many more.

Tracks from more than thirty CD recordings are used on movie soundtracks such as La Grande Bellezza and Arrival, and the ensemble has worked on film projects with Danish documentarist Phie Amboe and Oscar-nominated Icelandic composer Jóhann Jóhannsson.

During 2018 the ensemble featured in Kaija Saariaho's opera Only the Sound Remains with performances at Palais Garnier in Paris, Teatro Real in Madrid and Lincoln Center.

In January 2019 Theatre of Voices gave a sold-out concert in the new Elbphilharmonie great hall in Hamburg, which included the world premiere of Michael Gordon’s new work A Western, based on the film High Noon.