Oker are a Norwegian improvisational quartet made up of percussionist Jan Martin Gismervik; trumpeter Torstein Lavik Larsen; double bassist Adrian Fiskum Myhr; and acoustic guitarist Fredrik Rasten. Their all-acoustic sound is highly atmospheric, based on instrumental textures and static harmonies rather than melody and polyphony; in addition to drones, the group constructs gently rocking chords floating on a foundation of arco bass. Although lacking in overt drama, the music is richly colored, particularly given Oker’s penchant for using extended techniques. The percussive dimension is especially pronounced; in addition to Gismervik’s resonant and sensitive drumming, both double bass and guitar emphasizing staccato sounds, the former with the wood of the bow as well as pizzicato playing, and the latter with creative plucking on either side of the bridge. An important element in the group’s aggregate sound is Larsen’s use of air notes and other unpitched sounds, which complement the harmonics from the string instruments.