The Lydian musical scale is a rising pattern of pitches comprising three whole tones, a semitone, two more whole tones, and a final semitone. This sequence of pitches roughly describes the fifth of the eight Gregorian (church) modes, known as Mode V or the authentic mode on F, theoretically using B♮ but in practice more commonly featuring B♭ (Powers 2001). Because of the importance of the major scale in modern music, the Lydian mode is often described (or learned) as the scale that begins on the fourth scale degree of the major scale. The Lydian scale is often used in jazz.
The Lydian mode in music theory
Ancient Greek Lydian
The name Lydian refers to the ancient kingdom of Lydia in Anatolia. In Greek music theory, there was a scale or "octave species" based on the Lydian tetrachord, extending from parhypate hypaton to trite diezeugmenon, equivalent in the diatonic genus to the modern major scale: C D E F | G A B C. (In the chromatic and enharmonic genera, the Lydian scale was equivalent to C D♯ E F | G A♯ B C and C E E↑ F | G B B↑ C, respectively, where "↑" signifies raising the pitch by approximately a quarter tone) (Barbera 1984, 240). Placing the two tetrachords together, and the single tone at bottom of the scale produces the Hypolydian mode (below Lydian): F | G A B C | (C) D E F. Placing the two tetrachords together, and the single tone at the top of the scale produces the Hyperlydian mode (above Lydian), which is effectively the same as the Hypophrygian mode: G A B C | (C) D E F | G.
Medieval Lydian mode
The eight Gregorian modes: f
In the Middle Ages and Renaissance, this mode was described in two ways. The first way is the diatonic octave species from F up to F an octave above, divided at C to produce two segments: F–G–A–B–C and C–D–E–F. The second is as a mode with a final on F and an ambitus extending to F an octave higher and in which the note C was regarded as having an important melodic function. Many theorists of the period observed that B♭ is used more typically than B♮ in compositions in Lydian mode (Powers 2001).
Modern Lydian mode
Because of the importance of the major scale in modern music, the Lydian scale is sometimes described as a major scale with the fourth scale degree raised a semitone, e.g., a C-major scale with an F♯ rather than F♮. It is also sometimes described as the scale or mode that begins on the fourth scale degree of a major scale, e.g., the sequence of pitches in C-major when beginning on F. Consequently, the Lydian scale consisting only of white notes on a piano begins on F: F G A B C D E F. Students often learn about Lydian mode as compared to major mode via the above characteristics.
Triads within Lydian mode
In Lydian mode, the tonic, dominant, and supertonic triads are all major. The subdominant is diminished. The triads built on the remaining three scale degrees are minor.
Cross-perception between Lydian and Major
A modern listener's extensive experience with tonality may lead him to perceive a piece in Lydian mode as sounding in the parallel major. She may perceive the raised fourth scale degree as an applied leading tone, perhaps as part of the applied dominant chord V/V. Conversely, listeners may perceive Lydian mode where it is not intended. For example, a piece of music in C major that emphasizes the F major chord before establishment of the C major tonality may sound like it is in F Lydian due to the B♮s.
Modern usage of Lydian mode
A rare, extended use of the Lydian mode in the Classical repertoire is Simon Sechter's 1822 Messe in der lydische Tonart (Mass in the Lydian Mode) (Carver 2005, 76). A more famous example from around the same time is the third movement of Ludwig van Beethoven's String Quartet No. 15 in A minor, Op. 132 (1825), titled by the composer "Heiliger Dankgesang eines Genesenen an die Gottheit, in der lydischen Tonart" ("Holy Song of Thanksgiving by a Convalescent to the Divinity, in the Lydian Mode"). The alternating passages in F use the Lydian scale with sharp fourth scale degree exclusively. Anton Bruckner employed the Lydian scale is his motet Os justi (1879) more strictly than Renaissance composers ever did when writing in this mode (Carver 2005, 74–75).
Barbera, André. 1984. "Octave Species". Journal of Musicology 3, no. 3 (July): 229–41. http://www.jstor.org/stable/763813 (Subscription access) doi:10.1525/jm.1984.3.3.03a00020
Benward, Bruce, and Marilyn Nadine Saker. 2009. Music in Theory and Practice, eighth edition, vol. 2. Boston: McGraw-Hill. ISBN 978-0-07-310188-0.
Carver, Anthony F. 2005. "Bruckner and the Phrygian Mode". Music and Letters 86, no. 1:74–99. doi:10.1093/ml/gci004 (Subscription access)
Jones, George Thaddeus. 1974. Music Theory: The Fundamental Concepts of Tonal Music Including Notation, Terminology, and Harmony. Barnes & Noble Outline Series 137. New York, Hagerstown, San Francisco, London: Barnes & Noble. ISBN 978-0-06-40137-4.
Miller, Scott. 2002. Mel Bay's Getting Into … Jazz Fusion Guitar. Pacific, Missouri: Mel Bay Publications. ISBN 0786662484.
Powers, Harold S. 2001. "Lydian". The New Grove Dictionary of Music and Musicians, second edition, edited by Stanley Sadie and John Tyrrell, 15:409–10. 29 vols. London: Macmillan Publishers. ISBN 978-1-56159-239-5 (set) ISBN 978-0-19517-067-2 (set) OCLC 44391762 (set) OCLC 248649842 (v. 15) OCLC 249589729 (v. 15, reprint with minor corr.) LCCN 00-55156 or 00055156 (set)