Efterklang (the Danish word for reverberation) is a post-rock group formed on January 2001 in the Danish capital, Copenhagen. The group consists of five core members and a sixth member who makes films for their songs. When performing live, these six members are also joined by violinist Helianne Blais and trombonist Niklas Antonson. They have released albums on the British/American record label The Leaf Label, but also have their own record label called Rumraket (the Danish word for space rocket).

http://en.wikipedia.org/wiki/Efterklang