Her er eg fødde (excerpt), sung by Brita Bratland (Bratland, 1987, track 1)
In slått playing and folk songs there is often a flexible intonation; one note is micro-varied in intonation from one phrase to another, from one performance to another. This is one of the variability methods of the performance.
'Our folk music has been characterized by many tonal traits that make it not fit easily into the tempered major and minor system. On the surface, there is a lot that indicates that the vocal music was quite strongly connected to the minor scale and the modal scales. The slåtter on fiddle and Hardanger fiddle were rather connected to major scales, but there are also many touches of modality and mixed scales, and maybe natural scales too. … Because we operate with many half high intervals, folk music tonality will, so far as intonation is concerned, be based on far broader frames than those accepted in art music, that is built upon the tempered scale system. These nuances can be documented through half high thirds, sixths, fourths and sevenths'. (Nyhus, 1993b, pp. 193-194, my translation)
'Pitch measurements of older performers have shown great variations in placing of the notes. Not least Reidar Sevåg has, through measurements of older ‘langeleik’ playing, shown that while the octave and the fifth have had set positions, other intervals have had large amounts of variation. … Quarter tones are also among the older expressions, but maybe this is not the best expression to specify the notes in folk music. Folk music never has such small pitch movements as a quartertone. … The pure intervals can not be covered by this expression. Neither can the minor third, that is 16 cents over tempered, or the low throat fourth, that is 20 cents over tempered. Some call these notes blue notes, and that is a cool name, but from my opinion, gives too much association in the direction of blues and jazz, where one thinks that the note has slid in a movement, often upwards, in the area between minor and major. Half high and neutral pitches are the expressions that have been mostly used in the educational institutions in this country. We still don’t have any common word for all the non-tempered notes. About the half high fourth note, that in natural scale is the 11th note in the line, I think it is relevant to call it natural fourth, and thus separated from other non-tempered notes. Its placement is absolutely not ‘between’ other concepts when in use, but has an independent life and natural place in music all over the world.' (Ofsdal, 2007, p. 127, my translation)