Eivind Groven (1901-1977) was a Norwegian composer and musicologist, as well as being highly skilled at playing both the hardingfele (Harding fiddle) and seljefløyte (willow flute). He was unique among Norwegian composers in that he had an innate appreciation of the advanced tonal, rhythmic and structural characteristics of folk music, and because he possessed outstanding analytical and creative abilities. Groven's major works include two symphonies, a piano concerto, Renaissance (a symphonic poem in five movements), Historical Visions, the suites Symphonic Slåttar 1 and 2, Hjalarljod, From Saga towards Ballad, The Bridegroom, Olav Liljukrans, Margit Hjukse and Dream Ballad (also performed as a ballet). A number of his works have become part of the standard repertoire of contemporary Norwegian music. The overture Hjalarljod in particular, commissioned for the 900th anniversary of the city of Oslo, has achieved wide-spread popularity, and the principal melody of his first symphony won a competition to become the signature theme for the Norwegian State Radio.
In 1927, Groven published his thesis Naturskalen (The Natural Scale, 1927), a pioneering work in which he examined the use of melodic features of vocal and instrumental folk music that might have been derived from the so-called 'natural' scales and playing technique used on the seljefløyte. The 'natural' scale of the title refers to a system of tuning, called just intonation, which is comprised of acoustically pure intervals from the overtone series. Two of his subsequent works, Temperering og renstemming (Tempered and Just Intonation Tuning, 1948) and Renstemningsautomaten (The Automatic Just Intonation Tuning, 1968), develop an extensive analytical system of harmony based on just intonation, and address the familiar problem of tuning keyboard instruments in just intonation.
Like Hungarian composer Bela Bartok, Groven was also highly regarded as an ethnomusicologist. In addition to his numerous compositions and theoretical writings, Groven collected more than 1,000 recordings of Norwegian folk musicians, and transcribed 1,970 folk tunes. The application of Groven's theories about tuning can be found in both his own 'classical' compositions and these transcriptions of traditional 'folk' tunes. He even constructed a special type of organ capable of playing in just and other tuning systems. Following his death, Eivind Grovens Institutt for Renstemming (Eivind Groven's Institute for Just Intonation) was established so that his work in this area could be continued. The Institute, in Oslo, Norway, houses most of Groven's manuscripts, scores, recordings, transcriptions, and instruments (including two justly tuned organs).