This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (December 2008)

The Hypolydian mode, literally meaning 'below Lydian', is a musical mode or diatonic scale of ancient Greece^{[citation needed]} that was based upon the Lydian tetrachord: descending (the way Ptolemy and Boethius described it), a series of falling intervals of a semitone followed by two whole tones. The rising scale for the octave is a single tone followed by two conjoint Lydian tetrachords. This is the same as playing all the white notes of a piano from C to C: C | D E F G | (G) A B C (ascending, in the modern reckoning). Confusingly, this scale in medieval and modern music theory came to be known as the Ionian mode.

However, from as early as the time of Hucbald the Hypolydian mode – even more than the corresponding authentic mode, the Lydian – was characterized by the predominance of B♭ instead of B♮ as the fourth degree above the final (Powers 2001).

The medieval music scholars, misunderstanding the Latin texts by Boethius of how the Greek modes were reckoned, used the term Hypolydian to describe the sixth mode of church music.^{[citation needed]} This mode is the plagal counterpart of the authentic fifth mode, which Boethius dubbed Lydian.^{[citation needed]} The ecclesiastical Hypolydian mode is based on the relative scale of 'white notes' from F to F, with the musical dominant, the reciting note, or tenor at the major third on the scale (or A, in the F to F scale). The melodic range of the ecclesiastical Hypolydian mode is from C, the perfect fourth below the tonic, to the C a perfect fifth above.

[edit] Sources

• Powers, Harold S. 2001. "Hypolydian". The New Grove Dictionary of Music and Musicians, second edition, 29 vols., edited by Stanley Sadie and John Tyrrell, 12:38. London: Macmillan Publishers. ISBN 978-0-333-60800-5 OCLC 44391762