The vocal ensemble Trio Mediæval was founded by Linn Andrea Fuglseth in Oslo in 1997. For sixteen years, the three original members Anna Maria Friman, Linn Andrea Fuglseth and Torunn Østrem Ossum constituted the trio. In December 2013, Torunn left the group. Linn Andrea and Anna Maria are now joined by Berit Opheim, who has been singing with the ensemble regularly since 2010.
The trio's core repertoire features sacred monophonic and polyphonic medieval music from England, Italy and France, contemporary works written for the ensemble, as well as traditional Norwegian, Swedish and Icelandic ballads and songs, mostly arranged by the group members. During the last eight years, the trio has developed exciting collaborations with both individual musicians as well as larger ensembles/orchestras.
The trio has collaborated with a multitude of contemporary composers, including Anna Clyne, Gavin Bryars, William Brooks, Ivan Moody, Sungji Hong, Oleh Harkavyy, Bjørn Kruse, Trygve Seim and Andrew Smith. As a result of a cooperation in 2005 with the New York based composer trio Bang on a Can consisting of Michael Gordon, Julia Wolfe and David Lang, and the musikFabrik Cologne, the trio premiered Shelter, the group's biggest multi-media contemporary music project to date. Shelter premiered in Cologne, Germany, and it was fully staged the same year at the Brooklyn Academy of Music. Julia Wolfe was so fascinated by the trio's voices that she wrote a piece for them entitled Steel Hammer. Together with the Bang on a Can All-Stars, the trio premiered Steel Hammer in New York's Carnegie Hall in November 2009, and recorded it in 2011. In May 2013, the Steel Hammer was performed in Europe in Bruges, Uppsala Konsert & Kongress, and at the Barbican Centre/LSO in London. The Bang on a Can collaboration also resulted in the full orchestral piece Reason to believe by David Lang, that the Trio Mediæval and the Norwegian Radio Orchestra premiered in Oslo in October 2011.