He's performed admirably in free, jazz-rock, and quasi-new age situations since the '60s. Andersen studied bass and the Lydian Chromatic Concept of Tonal Organization with George Russell, and also played with him during the '60s and '70s. He also studied with Karel Netolicka. Andersen began playing at various festivals in Norway during the late '60s. He was tapped by Don Cherry for his first appearance outside Norway at the Berliner Jazztage in 1968. Andersen worked with Jan Garbarek from 1969 to 1973, and played with Russell, Sonny Rollins, Karin Krog, Sam Rivers, and Paul Bley at various festivals. He also worked with Bley, Rivers, Joe Farrell, Dave Friedman, Barry Altschul, Steve Kuhn, and Sheila Jordan in New York during the early '70s. Andersen backed vocalist Radka Toneff, and led quartets that featured Knut Riisnaes, Jon Balke, Paal Thowsen, Juhani Aaltonen, and Lars Jansson in the '70s and early '80s. During the '80s, he performed and recorded with Alphonse Mouzon, John Taylor, and Bill Frisell. Andersen led the quintet Masqualero, with Jon Christensen, Balke, Tore Brunborg, and trumpeter Nils Peter Molvaer. They toured England and Europe, while recording during the '80s. Andersen began recording as a leader for ECM in the early '90s and has released such albums as 1990's Sagn, 1997's Hyperborean, 2001's Karta, 2004's The Triangle, 2005's Electra, 2008's Live at Belleville, 2012's Celebration, and 2013's Under the Rainbow. In 2014, Andersen paired with drummer Paolo Vinaccia and saxophonist Tommy Smith for the trio album Mira. ~ Ron Wynn