15. Cadential 6-4 Chords
Tucked into the study of harmonic cadences is the so-called cadential 6/4 chord. A cadential 6/4 chord is not actually a cadence on its own, but it is sometimes used in harmonic cadences that move through a dominant function; specifically the [V] or [V7] chord. It consists of a second inversion tonic triad, [I 6/4] or [i 6/4], that moves to a root position dominant chord, [V] or [V7]. Since it necessarily moves to a dominant chord, cadential 6/4 chords are only present in harmonic cadences that also move through a dominant function: the Authentic Cadence, Half Cadence, and Deceptive Cadence. A Plagal Cadence does not move through a dominant function and therefore cannot make use of a cadential 6/4 chord.
Cadential 6/4 chords are possible in cadences that move through dominant
There is something very unique about the cadential 6/4 chord that borders on duplicity. Tonic triads, by definition, have a tonic function. A cadential 6/4 chord is a tonic triad based on the specific pitches included in the chord, “Do - Mi - Sol”. However, despite its pitch make-up, this chord masquerades as a dominant function sound and is not perceived by the listener as a tonic function. This duplicitous effect is particularly true when the second inversion tonic triad is followed by a dominant chord, specifically the [V] or [V7] chord. These two chords in effect merge together and act as a unit or a team and complement each other. A cadential 6/4 chord prolongs the tense feeling of a dominant function and strengthens the expectation of tonic for the listener.
In four part harmony, a cadential 6/4 chord features three markers that help a listener recognize its presence within a harmonic cadence:
REPEATED BASS
The bass voice (“Sol”) between the tonic triad in second inversion, [I 6/4] and the following root position dominant chord, [V] or [V7], is both reinforced by an upper voice and carried unchanged through the [V] chord. Recognizing two chords in a cadence that “sound” different but have a repeated bass voice alerts the astute listener that a cadential 6/4 chord unit may be present.REMAINING VOICES MOVE DOWN BY A STEP
Aside from the bass “Sol” that is carried through, the two remaining pitches of the [I 6/4] chord slide down by a step into their respective pitches within the [V] chord, usually Mi\Re (me\Re in minor keys) and Do\Ti.DOMINANT FUNCTION
Two [I 6/4] chord and the following [V] chord act as a unit to give the perception of a dominant function. Visually, going by pitch names alone, the I 6/4 chord “looks” like a tonic triad, but aurally it “functions” and is perceived by the listener as dominant.
Three characteristics of cadential 6/4 chords
The voice leading and usage of cadential 6/4 chords is fairly uniform within the compositions of the late Baroque (circa 1685 - 1750) and the Classical [circa 1750 - 1815] periods of European functional music evolution. Of course, as composers began to stretch the boundaries of functional tonal music, the “how” of cadential 6/4 chord usage was also taken beyond that “rules” seen above.
W. A. Mozart’s music, in particular, is an excellent source to study cadential 6/4 chords as they are strictly defined. The opening movement of his Piano Sonata No. 9 highlights the dominant function feel and the prolongation and strength that the cadential 6/4 chord adds to the function.
Cadential 6-4 Chords in W. A. MOZART "Piano Sonata No 9"
Cadential 6/4 Chords in W. A. MOZART “Piano Sonata No. 9”
The cadential 6/4 chord has survived the centuries and has also been deployed by other artists that do not stem from the European so called “classical music”. In the 1950s and early 60s, cadential 6/4 chords were a trendy inclusion in American rock ballads. Perhaps the most famous example is the song “Can’t Help Falling in Love”, as recorded by Elvis Presley in 1961.
Cadential 6/4 chords in “Can’t Help Falling in Love” as recorded by Elvis Presley
Cadential 6/4 chords in “Can’t Help Falling in Love” as recorded by Elvis Presley
British alternative rock band Muse takes a creative approach to the use of cadential 6/4 chords by pairing them with other dominant functions chords like the augmented triad built from the third scale degree in a minor key [III+]. In the song “Take a Bow”, band leader Matt Bellamy sustains the feeling of dominant throughout virtually the entirety of the song, constantly modulating through the circle of fifths until eventually touching on a total of 10 different keys. All of this creates a sense of constant tension that is on the cusp of resolving…but never quite gets there. This effect lends itself well to the intent of the song since the lyrics are intended as a denouncement of leaders in political power ignoring million voices that have risen in protest.
Cadential 6/4 chords in MUSE “Take a Bow”
Cadential 6/4 chords in MUSE “Take a Bow”
Some music theorists choose to label the cadential 6/4 chord as essentially a suspension of the dominant [V] chord. In figured bass notation, the suspension sees the 6 and the 4 above the bass voice resolve to the 5 and the 3 above the bass voice.
Option 1 for Cadential 6-4 Chord Notation
Other music theorists prefer to notate the cadential 6/4 chord more literally as a tonic [I] chord in second inversion, but linking it to the succeeding [V] chord by underlining both chords.
Both of these notations have merit and serve the purpose of identifying a cadential 6/4 chord at work. For the purposes of consistency, any reference in analysis to a cadential 6/4 chord in this course will be the notation as seen in Option 2 above.
The cadential 6/4 chord is, in a way, an algorithm that can be plugged into a harmonic progression to prolong and strengthen the tension created by a dominant function in order to increase the feeling of satisfaction once (and sometimes, “if”) this tension is resolved to tonic. It is a powerful tool that composers can utilize to further manipulate the sensations experienced by the listener.