Scalar Harmony in Scales
Scalar harmony refers to the scales used in songs or pieces of music. A scale may be defined as any collection of pitches occupying a region on the circle of fifths; compositional structures often feature shifting between different scale collections over time – sometimes within single sections – which often has expressive implications and dramatic results, for instance Fleetwood Mac’s “The Chain,” features such an effect where there is an unexpected momentary transition from neutral collection IV (IV) to sharper collection VI (VI), creating an effect which is difficult to explain harmonically but powerful and memorable – often powerful and memorable!
General, any particular scale can be described by its interval pattern and tonic note; these elements of a scale often combine into what’s called “key signatures”, an easy system for identifying which scale was used in any particular piece of music.
Most musical scales are octave-repeating, meaning their interval pattern repeats itself every octave. We can characterize this repetition by describing a set of chords generated when translating a three-note chord uniformly over a scale (as discussed previously). This description, known as an orbit cover, forms the basis for many structures described below.
A scale can be studied as an ensemble on a pitch-class collection, and from this analysis there exist various scalar harmony theoretic models that can be built. These models have both theoretical and practical applications.
Scalar-harmony theory’s most powerful tools involve understanding how scales and chords relate. For instance, hexatonic scales offer greater harmonic possibilities than pentatonic ones due to having nine tones rather than seven. While these additional tones add depth and variety when it comes to harmonization and melodic development, they may complicate finding an appropriate chordal form for any given piece of music.
Scalar Harmony in Space
Scalar collections within a chord segment may change at any time; sometimes this shift coincides with tonal center changes; for instance, The Beatles’ “Penny Lane” features such an example as its verse is in Mixolydian while its chorus changes to Ionian; similarly Kenny Rogers’ “Love Will Turn You Around” shifts between narrow mixolydian melodies to expansive Ionian harmony (Example 10).
Shifting collections often have expressive implications that cannot easily be understood through harmonic or linear analysis. A momentary shift such as that seen in Then Came You may evoke large-scale formal structures, or it may simply signal emotional change; often times it can be unclear whether these momentsary shifts should be seen as scaler shifts or simply emphasis shifts; both terms can often be used interchangeably.
Scalar Harmony in Time
Scalar shifts occur when chordal scales move outside their expected region on the circle of fifths, often accompanying tonal center shifts. Although their exact patterns differ widely between songs; for instance, in “Then Came You,” its cadential IV might either return to an Ionian collection or anticipate Mixolydian scale depending on your understanding of its VII segment interval composition.
Shifting scalar collections do not always correspond with tonal center shifts, which define larger-scale formal structures within a piece of music. But they often have similar expressive implications: for instance, they may delineate and reinforce structural boundaries or communicate a sense of tonal change such as Kenny Rogers’ verse-refrain melody in “Love Will Turn You Around” transitioning abruptly into Duran Duran’s Ionian chorus in “Rio.”
Scalar shifts can also be used to emphasize certain pitches within a chord’s scale degree content, creating more precise forms of expression. For instance, Fleetwood Mac’s “The Chain” opens with a simple arrangement of scale degrees i, v and vii which are relatively neutral; when switching over to Idom7 chord, their lower form creates an extremely sharp lean.
Scalar harmony can also be applied to individual melodic segments. A popular harmonic progression in pop music involves modulations from C minor to F minor and G major respectively, each time with differing scale-degree mixtures introduced at certain points. This shows how this approach can highlight various melodic forms while creating tension within songs; one reason many popular composers favor using scale degree alternations instead of traditional key signatures.
