To set the ball rolling gently, let’s initially agree that a mode is a scale. It is a certain kind of scale admittedly but a scale nonetheless. A scale however is not necessarily a mode.
Scales vs Modes
When we mention the word scale with a reference to music, we are commonly referring to a series of pitches that can ascend and or descend in a particular pattern.
Modal patterns are a branch of these scales in just the same way as scales in a key or some of the more exotic ones that sit comfortably just outside a given key, like the octatonic or chromatic scale.
Tonal scales, ones that directly link to a key are most frequently major or minor. There are several variations of the minor scale including the harmonic, melodic and natural.
Each of these has a slightly different selection of intervals or gaps between each of the pitches. These can be expressed as semitones, tones, or other larger intervals that when combined into a scale offer a distinct quality.
The harmonic minor, for example, has a characteristic minor third in it that I have often heard students refer to as making the scale sound Arabic.
In contrast, the melodic minor changes its intervals and thereby pitches, depending on whether it is ascending or descending. This is an echo of the modal system that came before the advent of tonality as we’d recognise it today.
The major scale is well-behaved and remains constant. It can be constructed using the following pattern of tones (T) and semitones (ST) – T, T, ST, T, T, T, ST.
Equally, the chromatic scale presents itself as a regular series of semitones ascending and descending. Because of its semi-tonal nature, it does not belong to a particular key.
The history of modes is a lengthy one heralding from the Ancient Greeks through to the far end of the late Renaissance. As you might anticipate, over this extended duration of time the concept of modes developed considerably.
What we often refer to today as modal orientates around diatonic modes of which there are seven. On the other side of a similar coin are the church modes or Gregorian modes, that a more closely related to those from Ancient Greece. There are eight Gregorian modes.
Before placing the Ancient modes to one side, it may be of interest to know how closely associated these modes were with human emotions. Such interpretations of the modes come from scholars like Guido of Arezzo (995-1050), and Adam of Fulda (1445-1505).
What’s fascinating is the consensus regarding the character of these modes that seems to be consistent over centuries.
Hypodorian mode is described as sad by each of these gentlemen, whereas, the Lydian mode in contrast is universally happy. The Phrygian mode is the one to watch out for described as mystic and capable of inciting anger.
The modal system that remains in use despite the transition to tonality in the Baroque period, works like this. Each mode is based on a different starting note of a major scale. This starting note effectively becomes the tonic.
On paper like this, it may not appear as if these seven modes would sound noticeably distinct, but they do.
Beginning with the Ionian mode, this is a direct copy of what we would describe as a major scale.
In contrast, the second mode, called the Dorian, brings a new colour sounding somewhere between a minor and a major scale. The notes, if you adopt the C major scale as a starting point give the following notes; D, E, F, G, A, B, C.
The fifth mode is called Mixolydian, and has a different set of tones and semitones with the resulting scale being; G, A, B, C, D, E, F.
The sixth mode, the Aeolian is often referred to as the natural minor scale and provides a lovely crossover between tonality and modality.
In a very similar way to scales like the major and minor, modal scales in this form each have a slightly different series of intervals. Commonly, students approach an exploration of modality using just the white notes on a keyboard although transpositions of any mode are valid and encouraged.
Modes have featured extensively in Jazz. Popular as a form between the 1950s and 1960s Modal Jazz offered performers a route away from tonality into a new colourful sonority.
Listen to Miles Davis’s album from 1959 titled “Kind of Blue”. Modality allows Miles Davis to step away from the furious, virtuosity of Bebop and Hard Bop and discover a fresh voice that came as a surprise to many of his fans.
Both scales and modes have more to tell us. Olivier Messiaen, (1908-1992), devised his own set of modes. These he titled Modes of Limited Transposition. Not only do these draw on the earlier concepts of modality, but they successfully contributed to Messiaen’s captivating sound.
Why limited modes? Unlike the modes discussed above, Messiaen’s modes deliberately have an inbuilt limit to their possible transpositions.
Taking the first mode as an example, Messiaen is using the whole-tone scale. Regardless of which degree of the scale you begin this series of tones, you will always produce the same scale.
The second mode, as the name suggests, has two possible transpositions available and is usually referred to as the octatonic or diminished scale.
The modal concept Messiaen developed follows this pattern except for mode three which has four transpositions and four, five, six and seven each with six transpositions.
Messiaen bridges the scale and modal territories uniquely. He also highlights interdependency. There are a huge number of different types of scale especially if you consider those that originate across the wider world, not only Western Culture.
Different temperaments and divisions of the octave facilitate a bewildering lineup of vibrant scales, many that sound wrong to Western ears.
Among that cosmic collection of scales are modes. They are a critical component of the scalic family looking back to ancient times as well as being embedded into contemporary compositions.