Music Theory – Seventh Chords

seventh chords music theory

Seventh chords are an integral component of most musical genres and provide an immediate sense of movement and tension. Dissonant seventh chords have also been employed as an emotional hook in certain songs.

Each seventh chord possesses its own specific qualities based on its composition of triads and seventh intervals. Here are five of the more frequently encountered seventh chords:

Major Seventh

Major seventh chords are built upon triads, adding an octave-above seventh note. Their bright, melodious sound makes them popular choices in jazz music and other forms of light music.

Most textbooks refer to chords by their type of triad and seventh; for example, Cm7 chord would represent either a major-major seventh chord, or simply major seventh chord. However, many musicians also employ an alternate nomenclature wherein either or both qualities – triad and seventh – are implied within its name.

To transform a major seventh chord into a diminished one, simply lower C and E by half step (to B and G respectively) to remember there is a distinction between these triad qualities. Practice creating each type of chord until they become second nature to you.

Half-Diminished Seventh

The ii7/b5 chord, commonly referred to as the half-diminished seventh, is one of the most frequent seventh chords found on diatonic II chords in minor keys, where it often acts as either a dominant function or leads into major tonic cadences. Additionally, this chord appears in dominant V-type progressions like Wood Dove chorale’s iv7/b5.

Most textbooks define seventh chords by their triad type and seventh quality; when used formally (such as in formal settings such as i7/minor or V7/major), these conventions can be disorienting to beginners in functional harmony since naming systems derived from such conventions don’t follow interval qualities directly, but rather focus on specific combinations of triad and seventh combinations.

To identify a seventh chord’s interval qualities, simply imagine its root triad and write down its third and seventh notes (for instance D). Next consider its key signature and any accidentals applicable to its root triad triad’s root.

Fully-Diminished Seventh

The diminished seventh chord has long been used to express intense feelings such as anxiety and distress. Composers such as Bach, Haydn, Beethoven and Wagner all made use of this chord in their works in order to create tension that eventually was relieved with dominant harmony resolutions.

This type of chord produces an unpleasant dissonant sound when extended beyond its root octave, due to how it interacts with tonic triad and clashes with other intervals in scale; for this reason, fully-diminished seventh chords should generally be avoided.

Fully-diminished seventh chords that share three pitches with dominant sevenths but cannot be constructed solely using diatonic notes are known as fully-diminished seven chords rooted on leading tone chords; rather they require borrowing notes from their parallel key as an added note for construction. Due to this fact, these chords generally function more as appoggiatura chords for dominant sevenths rather than as primary-function chords of their own, making them similar secondary-function diminished sevenths while adding their unique, dissonance.