A seventh chord can be formed by adding an interval one step above a triad. This results in four-note chord (tetrachord).
To identify a seventh chord, locate its root and draw an extra-long snowperson on the staff representing its notes, which correspond to those in a major triad.
Major
Seventh chords consist of a triad and an interval of one seventh from their roots, creating dissonant sounds and tension within music. Seventh chords can add emotions and colors to a composer’s music while creating tension at times.
Quality in seventh chords can be determined by their root key signature, so to identify its quality simply imagine this and write it on a staff. For example, the C# major seventh (C-E-G-B) contains its root as a major triad; E and G are sharp in this key of C# so they have been written half step lower resulting in diminished triad.
A seventh chord can be identified using its root letter name, its quality of seventh note and clef note number, shorthand symbol for it as well as pitch class designation; for instance the Cm/Eb seventh features both minor third and perfect fifth above its root note.
Minor
Minor seventh chords add tension, warmth, and soulfulness to music. Like their major counterparts, they consist of four-pitch class clumps with the addition of a minor seventh.
Minor seventh chords consist of the root note plus two minor thirds and perfect fifths above it, such as A minor has A for its root note, C for minor thirds, and E for perfect fifths. The same process for identifying chords applies equally well when it comes to minor sevenths of any key.
Minor seventh chords may be less widely heard than their major counterparts, yet they also serve an integral function tonally. With the exception of those built on scale degree 11 which could undermine tonic harmony stability, most seventh chords constructed at other scale degrees behave predictably and respond to similar rules for approaching and resolving them, such as those discussed above with IV and V7 chords as examples.
Dominant
The dominant chord is an effective tool for building tension and anticipation in music compositions. Consisting of a major triad with a flatted seventh above its root note, this chord produces dissonant tones which require it to resolve back into tonic chord. While more commonly associated with rock music, its use can also be found classical music as well as blues tracks like Carl Perkins’ classic track “Blue Suede Shoes.”
Dominant seventh chords provide an easy way to switch keys due to their close relationship to the root of the scale, as well as concluding a tonal phrase or creating an exciting climax.
To identify a dominant seventh chord, it’s necessary to be familiar with its characteristic sound of each interval. Keep in mind that they are stacked differently than traditional major or minor chords; therefore, learning to hear this difference is vitally important.
Mix
Seventh chords are four-note chords created by adding an interval of a seventh above the root of a triad, making the chord dissonant but often used by musicians as an expressive way to add emotion and color to their compositions.
Similar to triads, seventh chords can be identified by their voicings and qualities. Like its triadic cousins, seventh chords may also be inverted for inversion purposes – this topic will be explored further in Chapter 9: Inversion and Figured Bass.
To develop the desired seventh chord quality, begin by noting the Roman numeral wherein it appears in your score. Next, determine its lowest note if not its root note and identify any accidentals needed.
Example G half-minus seven chord: C-Eb-Gb-Bbb (B double flat). These notes are then stacked in closed spacing as seen below; their generic interval above the root name appears below this list.