Seventh chords add depth, emotion and complexity to chord progressions – no matter if it be jazz, R & B, blues or pop. Seventh chords are an integral component of most song structures and should always be included within your musical arsenal.
A seventh chord can be defined as any triad with an additional note that sounds seven steps higher.
Definition
Seventh chords are four-note harmonies which feature an interval of the seventh above the root triad, making them inherently dissonant and necessitating careful voice-leading in order to sound harmonically balanced. Yet their inherent dissonance allows sevenths to add emotion and depth to regular major or minor chords.
As a rule, seventh chords are generally named according to their type of triad and quality of seventh above it; for example, an I7 chord would refer to a major triad with a minor seventh above.
A seventh chord’s four qualities are major, minor, diminished and half-diminished, each producing different effects on listeners. To understand them better, imagine an unlowered major triad as its lower counterpart and lowering each by one semitone to become its respective counterpart; repeat this process for each quality of a seventh chord.
Origin
Seventh chords can be constructed by adding a seventh interval above the root of a triad, then arranging their remaining notes into thirds to form a root-third-fifth-seventh structure. Although initially dissonant, seventh chords require special forms of resolution in order to sound well.
As they first emerged as embellishments or non-chord tones to emphasize movement in certain directions, dissonant tones quickly became accepted as integral parts of tonal harmony.
Seventh chords can be classified according to their intervallic content and relationship to the tonic triad. Chords built on scale degrees 1, 5, and 7 are considered dominant seventh chords (V7, V6, and vii7) while chords built on me and le constitute half-diminished seventh chords that contain both diminished triads and minor sevenths, while those composed on re and ti are fully diminished seventh chords.
Scales
Seventh chords are four note chords composed of any scale. Since they do not follow a tertian structure, which forms dissonant seventh intervals with its root chord root note, seventh chords require “resolving down” to produce harmonious harmonic chords.
To create a seventh chord, start from the root of a triad and add notes a third, fifth and seventh above it. Depending on its quality of seventh intervals, this chord could either be major, minor, diminished or augmented.
Seventh chords can be found in all forms of music from contemporary pop and rock to Baroque-era classical, making a solid understanding essential. Sevenths play an essential part in shaping chord progressions as they provide their basic feel and movement; harmonic modulations is used to add depth and texture to melodies like Clair de Lune by Claude Debussy is an iconic example of sevenths used in romantic melodies.
Variations
Seventh chords are highly adaptable, with many playing specific roles within pieces of music. Furthermore, their adjustability enables them to fit with various musical styles or moods; popular examples are major sevenths, dominant sevenths and half-diminished sevenths; while subdominant sevenths and leading-tone sevenths may only occasionally appear.
Major seventh chords are the foundation of seventh-chord arrangements. To form one, simply add an interval of major sevenths above any major triad (for instance C major triad is composed of root, third, and fifth notes; to create Cmaj7 chord add C to its end).
Also called C7 chords or dominant sevenths, dominant seventh chords are composed of adding a flattened minor seventh to a major triad, often known as C7. To further customize these chords you could remove one fifth, creating Maj7b7s or add sharpened ninths (#9s or 9s) at the top of the chord.