Continuing with Lachenmanns 'klangtypen', there can be a gradual transition between fluctuation and fragile timbre, if we consider natural microfluctuations of a sound. When Lachenmann describes the 'Fluktuationsklang', he turns to Chopins Etude op. 10 no. 1, fluctuations of natural harmonics in Ligetis "Atmospheres", 1 and Ravel's "Lever du jour" from Dapnis et Chloe. 2 These situations have vivid actions up and down, and are yet static by nature as the overall shapes do not develop. The Chopin and Ravel examples are guided by harmonic progressions establishing expectations and cycles.
Our 'fluctuation' recordings are closer to the stasis of Ligeti's fluctuations, which do not have progressions of harmony. They overlap with the 'shimmer' type, whisperings of Joyce, and concrete use of water sounds. Currentes came up with a good variety of extended sound fluctuations, leading to abstraction of the medieval instrumental group.