Seventh chords can help create tension in your music, particularly when they resolve into sonority with a falling-fifth (or rising-fourth) root motion.
As with triads, seventh chords can always be divided into thirds on the staff for convenient playback and interpretation. Their qualities correspond with scale degrees.
Major
A major seventh chord is an extension of a basic three-note triad, created by adding one note a major seventh interval above its root note (for instance C major triad has C-E-G); to make it into a seventh chord you would add another note one major seventh interval above C; giving rise to C E G B chord. You can identify such chords using its root and quality: root is lowest note in chord, quality determines whether chord is major minor diminished augmented; Roman numeral system also can identify inversion of seventh chords!
To recognize a seventh chord, start by reviewing its key signature and visualizing its root note stacked closely, along with any generic thirds, fifths and sevenths above it. For instance, if the root note of D is used as the chord’s root note, imagine drawing an extra-long snowperson using those notes – which could include F, A and C respectively as possible thirds, fifths and sevenths from that chord; write these down later before adding any accidentals from its key signature as needed.
Use the same process when open-spacing triads are being constructed; just be cautious with any doubled notes! Doubled notes may lead to confusion regarding different voicings of seventh chords, so it is necessary to practice identifying them both closed and open spacings.
An effective way to learn major seventh chords is through song progressions from popular songs that incorporate them. There are plenty of examples online, and they will give you a good sense of what each progression sounds like in context. With practice, you should become adept at recognising them without needing to refer back to charts; eventually your ears alone will allow you to recognize seventh chords in music!
Minor
Minor seventh chords are among the most frequent seventh-chords found in music, lending it more emotion and complexity than its basic triad chord counterpart. You may find this type of chord in modern genres such as R&B and soul music; older musical forms such as Debussy’s “Claire de Lune” may also employ it.
Seventh chords are composed by adding a note which falls at a seventh interval above the root of a triad. This note is commonly known as the seventh but could also be labeled with other names such as dominant seventh or major seventh. Chords usually comprise scale degrees 1 through 3, 3, 5, 7 but there may be exceptions.
As with triads, seventh chords can be identified by their root, quality and inversion. Their quality is determined by its root; which in this instance is determined by its bottom-most note – or sometimes both! Seventh chords may also be altered through augmenting or diminishing, with inversion indicated using symbols different than standard triad symbols.
C7 indicates a major-quality seventh chord (major triad + minor seventh), while symbols m(maj7) and aug7 signify diminished-quality seventh chords; any increase or decrease is indicated by adding +9 for an augmented seventh chord and -9 for a diminished seventh chord respectively.
As with triads, seventh-chords can be identified by their roots, quality, inversion and name; for now inversion will be discussed further in the Triads and Inversion chapter; instead students should identify seventh-chords by Roman numeral names. Students should practice altering triads into seventh-chords by changing one of the pitches in their upper voices into seventh chords before identifying it with root position writing its Roman numeral name and writing out short piano-and-voice excerpt. Finally they should identify chords by playing them and listening as to how they sound when listening closely as well.