Seventh chords can create a lusher sound than their triad counterparts, providing tension or release through either leaping or gradual movements.
Chords built on me and le are major seventh chords (contain a major third, perfect fifth and minor seventh) while those constructed using re and do are half diminished chords, consisting of both diminished triad and diminished seventh tones found only in harmonic minor.
Major Sevenths
As it relates to seventh chords, they can often be difficult to identify. Pop music frequently uses “7” as an umbrella term for any form of seventh that appears naturally within any key (for instance C7 refers to C major minor seventh – not C, E, G and B as on this site!). We use Roman numerals here instead so as to distinguish each seventh chord by quality of its triads and seventh interval content.
Memorizing these qualities won’t alter depending on the key, making seventh chords easier to make sense of in all keys. A fully diminished seventh is composed of a diminished triad stacked on top with a minor seventh added; it adds jazzy, silent-movie flair to your progressions!
Note that seventh chords based on sol and re contain a minor triad and minor seventh, while those built on do and fa feature major triads and major sevenths; this difference has an important bearing on their behavior as chords constructed on me and le.
Minor Sevenths
Seventh chords can introduce dissonance into a triad, so they must be approached and resolved carefully. Similar to triads, seventh chords can be classified by their intervallic content – those containing nonharmonic tones must resolve through falling-fifth root motion to achieve sonority that follows, hence why they’re frequently used as tonic harmonies in Western music. Chords built between scale degrees 11-22 tend not to feature prominently due to their dissonant sevenths threatening to undermine stability of their tonic triad counterparts.
As seen above, most minor key seventh chords can be identified using Roman numerals as labels for each seventh. Now it’s time to put all this knowledge to use – just be sure to listen closely as you play and use your ears when creating chords that sound good – plus don’t forget that 7th chords can also be inverted like triads for even greater soloing possibilities!
Dominant Sevenths
A dominant seventh chord can add dissonance to your music with ease, thanks to its inherent tension that stems from having a tritone interval between its third scale degree and flat seventh scale degree.
Third degrees are one whole step away from fifth degrees; therefore the interval of three whole steps creates an unstable and tensioned chord sound, adding drama to your music.
To form a dominant seventh chord, simply assemble a major triad on the root note of the key and add a minor third. This chord will contain both major and minor sevenths, creating the characteristically tense sound associated with dominant sevenths.
When playing a dominant seventh chord, be mindful not to move any low notes outside the staff (as this would alter its key) and instead move high notes up as needed so as to maintain a bass line in sync with its tonic note – this will prevent an excessively bitter sound while making reading easier for beginners.
Harmonic Sevenths
Minor scales utilize distinct intervals, producing chord progressions which differ from major key ones. In particular, minor key chord progressions will feature tonic chords as the tonic, subdominant chord and dominant chord while major scale chords will display supertonic and subtonic tones (III, VI and VII respectively).
Seventh chords tend to be more complicated than triadic chords due to their inclusion of dissonant sevenths that sound above the root note of the chord. Due to this extra pitch, seventh chords require special care when voice-leading them as opposed to performing them without special care and consideration.
The vii dim 7 chord in a minor key is particularly straightforward to voice-lead due to its preparation by its preceding I chord (C in bass voice). Once voice-led, its seventh of this triad naturally resolves via fifths into V chord as shown in Example 18-6 in tenor voice, making this chord the go-to choice when cadences end on IV (iv chord replacement).