The Hypolydian mode, literally meaning "below Lydian", is the common name for the sixth of the eight medieval church modes

Musical mode

In the theory of Western music since the ninth century, mode generally refers to a type of scale. This usage, still the most common in recent years, reflects a tradition dating to the middle ages, itself inspired by the theory of ancient Greek music.The word encompasses several additional...

 (Powers 2001b). The name is taken from Ptolemy of Alexandria's

Ptolemy

Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...

 term for one of his seven tonoi, or transposition keys (Powers 2001a). This mode is the plagal

Plagal mode

A Plagal mode may mean different church chanting modes, depending on the context.-In Western Practice:A plagal mode   is a musical mode, which is one of four Gregorian modes whose range includes the octave from the fourth below the tonic, or final, to the fifth above...

 counterpart of the authentic fifth mode

Lydian mode

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 modes, known as Mode V or the authentic mode on F, theoretically using B but in...

.

In medieval theory the Hypolydian mode was described either as (1) the diatonic octave species

Octave species

In early Greek music theory, an octave species is a sequence of incomposite intervals making up a complete octave...

 from C to the C an octave higher, divided at the final F (C–D–E–F + F–G–A–B–C) or (2) a mode with F as final and an ambitus

Ambitus

In ancient Roman law, ambitus was a crime of political corruption, mainly a candidate's attempt to influence the outcome of an election through bribery or other forms of soft power...

 from the C below the final to the D above it. The third above the final, A—corresponding to the reciting tone

Reciting tone

In chant, a reciting tone is a repeated musical pitch around which the other pitches of the chant gravitate, or by extension, the entire melodic formula that centers on one or two such pitches. In Gregorian chant, reciting tones are used for a number of contexts, including the chanting of psalm...

 or "tenor" of the sixth psalm tone—was regarded as having an important melodic function in this mode. The sequence of intervals was therefore divided by the final into a lower tetrachord

Tetrachord

Traditionally, a tetrachord is a series of three intervals filling in the interval of a perfect fourth, a 4:3 frequency proportion. In modern usage a tetrachord is any four-note segment of a scale or tone row. The term tetrachord derives from ancient Greek music theory...

 of tone-tone-semitone, and an upper pentachord

Pentachord

A pentachord in music theory may be either of two things. In pitch-class set theory, a pentachord is defined as any five pitch classes, regarded as an unordered collection . In other contexts, a pentachord may be any consecutive five-note section of a diatonic scale...

 of tone-tone-tone-semitone. However, from as early as the time of Hucbald

Hucbald

Hucbald was a Frankish music theorist, composer, teacher, writer, hagiographer, and Benedictine monk...

 the Hypolydian mode—even more than the corresponding authentic mode, the Lydian

Lydian mode

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 modes, known as Mode V or the authentic mode on F, theoretically using B but in...

—was characterized by the predominance of B♭ instead of B♮ as the fourth degree above the final (Powers 2001b). The melodic centering on F and A, as well as the use of B♭ instead of B♮, is illustrated in the accompanying example from the Requiem Mass introit, "Requiem aeternam".

Finer distinctions among the scale degree are sometimes made, with the D below the final called the "mediant", the lowest note, C, the "participant" (a tone functioning as an auxiliary to the mediant), the G, B, and B♭the "conceded modulations" (subsidiary degrees), and the lowest C, the final, F, and (rarely) the D the "absolute initials" (Rockstro 1880, 342).

Sources

• Powers, Harold S. 2001a. "Dorian". The New Grove Dictionary of Music and Musicians, second edition, 29 vols., edited by Stanley Sadie
  Stanley Sadie
  Stanley Sadie CBE was a leading British musicologist, music critic, and editor. He was editor of the sixth edition of the Grove Dictionary of Music and Musicians , which was published as the first edition of the New Grove Dictionary of Music and Musicians.Sadie was educated at St Paul's School,...
  
   and John Tyrrell
  John Tyrrell (professor of music)
  John Tyrrell was born in Salisbury, Southern Rhodesia in 1942. He studied at the universities of Cape Town, Oxford and Brno. In 2000 he was appointed Research Professor at Cardiff University....
  
  , 12:38. London: Macmillan Publishers
  Macmillan Publishers
  Macmillan Publishers Ltd, also known as The Macmillan Group, is a privately held international publishing company owned by Georg von Holtzbrinck Publishing Group. It has offices in 41 countries worldwide and operates in more than thirty others.-History:...
  
  . ISBN 978-0-333-60800-5
• Powers, Harold S. 2001b. "Hypolydian". The New Grove Dictionary of Music and Musicians, second edition, 29 vols., edited by Stanley Sadie
  Stanley Sadie
  Stanley Sadie CBE was a leading British musicologist, music critic, and editor. He was editor of the sixth edition of the Grove Dictionary of Music and Musicians , which was published as the first edition of the New Grove Dictionary of Music and Musicians.Sadie was educated at St Paul's School,...
  
   and John Tyrrell
  John Tyrrell (professor of music)
  John Tyrrell was born in Salisbury, Southern Rhodesia in 1942. He studied at the universities of Cape Town, Oxford and Brno. In 2000 he was appointed Research Professor at Cardiff University....
  
  , 12:38. London: Macmillan Publishers
  Macmillan Publishers
  Macmillan Publishers Ltd, also known as The Macmillan Group, is a privately held international publishing company owned by Georg von Holtzbrinck Publishing Group. It has offices in 41 countries worldwide and operates in more than thirty others.-History:...
  
  . ISBN 978-0-333-60800-5
• Rockstro, William Smyth. 1880. "Modes, the Ecclesiastical". A Dictionary of Music and Musicians (A.D. 1450–1880), by Eminent Writers, English and Foreign, vol. 2, edited by George Grove, D. C. L., 340–43. London: Macmillan and Co.