Seventh chords add another level of harmony that cannot be achieved using only triads alone, making them essential components of many musical genres such as Blues and contemporary pop music.
Similar to triads, seventh chords can be classified by their interval qualities to help you better understand their construction and performance. Doing this will enable you to craft harmonic sequences more easily.
Major
Seventh chords are essential in piano music across almost all genres. Their fuller and more complex harmonic landscape makes them the backbone of many popular song progressions and they should be part of any musician’s toolbox to expand their harmonic palette.
A seventh chord is a four-note chord composed of seven notes that adds one extra tone above the root of a major triad (1 3 5 7). Mathematically there are 64 types of seventh chords; five types are typically employed in western music: these are: major7, minor7, dominant7, half-diminished7 and diminished7 chords.
Seventh chords do not follow the rules set by scale degrees like triads do; rather they can be composed from any combination of triads and sevenths that come together into chords – hence their variety in names. Common examples are major-major seventh, minor-minor seventh, half-diminished seventh and diminished sevenths.
Minor
Minor seventh chords can be created by lowering both its third and seventh degree by half steps to make a major seventh chord minor in voice-leading terms; when used melodically this requires special consideration as they contain dissonant pitches which could add discordance in vocal harmony contexts.
Like triads, seventh chords can be combined in different ways to form different qualities. When written on the staff, these chords resemble an extra-long snowman with bottom, two middles, and head sections.
First among these qualities is the minor major seventh (Cm(maj7)), which is a regular major seventh chord with its minor third reduced to Bb. When raised one full step to Db, this changes into a dominant 7th (Dm(dom7)), often used as the root chord in popular songs and an excellent way of building finger strength while practicing rhythm! Furthermore, using this chord also offers great thumb picking technique practice!
Augmented
Augmented chords add an exciting musical twist. Composed by combining a major triad with an augmented fifth, they can produce an arresting sound and add tension-inducing tension that often finds its place in dramatic music.
As with diminished chords, augmented chords do not follow tertian harmony rules and can be used outside a tertian harmony framework. Sometimes called “diminished sevenths,” although in musical circles the term “augmented” is more popular.
As an example, the Lydian Dominant chord G9(#11) is an augmented upper structure triad (commonly referred to as simply “G augmented”) while its inversion Gb9(#11) serves as an augmented dominant (7th). While augmented sevenths may not be as common in music composition as major or minor sevenths, their distinctive sound can give your music a unique sound – for instance The Milk Carton Kids use one in their song Stealing Romance from their second-coming of Simon and Garfunkel to great effect – as Paul McCartney sings emotion-packed vocals by using an augmented seventh to heighten Paul McCartney vocals and Paul McCartney vocals on his vocals from Simon Garfunkel’s second coming.
Wandering
Western music’s fundamental harmonic building blocks are triads, composed of a root note, fifth note and seventh. Seventh chords take this concept a step further by adding another note – often called a ninth – adding another level of complexity and texture.
An altered dominant chord, commonly referred to as 7(b9) or 7alt in jazz music compositions, uses this chord combination to add a layer of mystery and unpredictability. Wayne Shorter’s tune Fall provides a wonderful example.
At the outset of this progression, a C dominant seventh chord in third inversion deceptively resolves to an F major triad via deceptive harmonic passing tones – shifting its tonality away from its dominant note via chromatic passing tones and creating new ambiguity within the chord itself. At the conclusion of the piece this sense of mystery continues with an evolving B dominant seventh in second inversion which gradually leads into A flat mediant major sonorities.