Musings

What are modal scales?

A mode is, in essence, a scale — a collection of seven pitches within the span of an octave — considered from a particular starting degree. When the same set of pitches is reordered to begin on a different pitch contained in the set, the sequence of intervals (distances between the pitches) changes, and with it, the sonic character. This shift in tonal centre alters the expressive quality of the mode: some are bright and expansive, others dark and tense, and some are more ambiguous in mood.

In the major scale, for example, beginning on the first degree (i.e. or, in musical contexts, treating it as point of departure and resolution, or as a sustained drone) yields the Ionian mode — the familiar “major scale” sound. Commencing instead on the second degree produces the Dorian mode: still stepwise (consisting of stacked whole tones and semitones, and no larger gaps) and diatonic (consisting only of pitches of a "parent" major scale), but with a flattened third and seventh note, imparting a cooler, more reflective quality.

The same principle applies to what is often referred to as the jazz melodic minor scale — "jazz" referring specifically to the form that retains its intervallic structure ascending and descending, in contrast to the classical melodic minor, which descends as the natural minor (with ♭6 and ♭7). It is instructive to note that the sole difference between the major scale and the jazz melodic minor lies in the third degree: major in the former, minor (♭3) in the latter. This single alteration has a profound structural consequence, reshaping the parent scale’s interval pattern and, by extension, the character of every mode derived from it. As you review the two lists above, observe how this one change (appearing in red across the melodic minor modal scale spellings) permeates the entire modal family.

When the modes of the major scale and the jazz melodic minor are considered together, they encompass the complete set of seven‑note, stepwise scales that contain the intervals of five whole tones and two semitones, and which avoid both chromatic clusters (as can be found in Neapolitan and bebop scales) and large leaps (such as the augmented second found in the harmonic minor and its modes).

Navigating the Major and Melodic Minor Modes

I have designed the chart below to demonstrate the relationships between the different diatonic and melodic minor modal scales. The spatial arrangement of the named scales in the chart is intentional: adjacent positions are related by the smallest possible pitch alterations, and the nature of the connection demonstrates precisely how to move from one scale to another. A diagonal move alters a single degree by a semitone, and the applied accidental (♯, ♭, ♮) corresponds with the direction of change, with ascension of the chart entailing gradual sharpening of tones and descension gradual flattening. Horizontal and vertical moves represent compound shifts, altering two degrees simultaneously as determined by the direction of movement. Vertical movement upwards entails the sharpening of both labelled degrees, and downwards the flattening of both. Horizontal movement to the right involves sharpening of the first identified degree and flattening of the second, with the opposite being true for movement to the left.

Simply put, ascending the chart entails raising notes and thus brightening of tonal colour and and the introduction of “light”, where descending entails lowering notes, darkening the sound and introducing “shadow.” The same connection thus carries a different expressive and technical implication depending on the direction of travel. One special case warrants attention: altering degree 1 changes the root of the scale. This can sometimes be avoided by travelling in the opposite direction. For example, the chart illustrates how the shift from Locrian to Lydian can be achieved with a single downward diagonal move, flattening the 1 to change from the pitches of, for example, D♭ Locrian to C Lydian. However, moving from D♭ Locrian to D♭ Lydian (i.e. keeping the same root note) requires ascending the chart, compounding the alterations that appear along the vertical route between the Locrian point of departure and Locrian destination (sharpening of the 2 + 5, then 3 + 6, and then 4 + 7).

Diagonal moves may also be compounded: two or more single‑degree alterations can be executed sequentially or combined into a single, larger leap. For instance, moving from Lydian Dominant to Dorian could be achieved in steps with two diagonals — first naturalising the 4th (♯4 → ♮4) to deliver an intermediate Mixolydian scale, then additionally flattening the 3rd (3 → ♭3) to reach Dorian — or as a compound diagonal, applying both changes simultaneously. In either case, the process involves stacking alterations to achieve a more substantial modal transformation.

Advice for Getting Started

A practical way to begin exploring the chart is to start from the familiar ground of the major scale and move diagonally between the internal columns, making one alteration at a time. For example, flattening the 7th degree transforms Ionian into Mixolydian; flattening the 3rd degree in addition to that yields Dorian, etc. Once you have worked through such a sequence, reverse the process to return to your starting point.

I highly recommend exploring the scales in "all twelve keys" (i.e. rooted on all twelve pitches of the chromatic scale) as a means of developing greater understanding and technical fluency. The above noted process of ascension or descension across the chart can, in principle, be continued indefinitely — at least within the limits of your instrument’s available pitch range. For instance, working down the chart from Lydian to Locrian by successive single‑degree alterations can be followed by flattening the 1st degree of the Locrian scale, thus producing a new Lydian scale rooted a semitone below the original starting pitch, from which the same sequence can be repeated, and so forth.

The modes of the jazz melodic minor, positioned in the outer columns, may be used to introduce more vivid harmonic colours, to refine the ear’s sensitivity to alterations, and — by moving between patterns that are likely to be less familiar — to enhance technical facility.

To ensure these ideas move beyond the realm of technical or theoretical exercise and become part of your personal musical vocabulary, aim to memorise them melodically. Strive to hear each transformation internally, to the point where you could sing the altered scale — whether out loud or silently — before playing it. This will help integrate the relationships shown in the chart into your intuitive, aural understanding of modal movement.

Happy practising!