The vocal ensemble Trio Mediaeval 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.