Common Practice music uses seventh chords only occasionally as standalone structures; typically they’re part of a chord progression with other chords. But in jazz genres like bebop or soul music, seventh chords are incredibly frequent and often appear alone.
When analyzing seventh chords, it’s essential to pay close attention to their figured bass numbers – these indicate how many inversions must occur for that particular seventh chord.
I7
When discussing seventh chord inversions, we refer to any chord where its root note is not the lowest note. Similar to triads, there are three possible seventh chord inversions – first, second and third – each consisting of a bass note stacked above other notes that form it. A major seventh chord would consist of four notes: B-D-F-G in its closed position would show this. These inversions correspond with 3/5/6 figures which will indicate how far between its root note and bass note is between these three numbers while 6 indicates how many notes stacked above its root note compared with how many there are above it.
I7
The dominant seventh chord, sometimes written as V7, is often considered the first inversion of a seventh chord and usually serves as the most dominant chord within songs. Additionally, its inversion known as I7 or “five seven” chord is sometimes also written out.
Roman numerals provide us with a crucial way of seeing seventh chord inversions: they reveal their exact interval structure even when written out with flats and sharps. You can use an instrument such as ukulele to help detect these intervals; but it would be smart to study music theory courses or books to gain more information so you know how best to interpret the information presented here.
Roman numeral symbols used to symbolize seventh chords reflect their quality as indicated by their underlying triad, with capitalization dependent upon this quality: uppercase for major (I7 or V7) triads and lowercase for minor or diminished ones (e.g. ii7 or viio7) triads. Some theorists additionally add lowercase letters after Roman numerals to denote half-diminished or fully diminished seventh chords: either an “m” (major half-diminished chord) or “o7 or Eb viio7) chord.
One major distinction between seventh chords and triads lies in their bass notes being doubled up into an upper voice of most triads, while not being repeated by seventh chords. Reason being, unlike triad’s bass notes, seventh chord tones do not offer compatibility for doubled vocal parts in equal measures. Due to this reason, it is necessary to learn figured bass for seventh chords so as to accurately identify which notes should be doubled in the bass. Figured bass is a system of musical analysis which determines a specific bass note for every inversion of a chord. Learn the figured bass notation used with slash notation that we’ve been covering in this lesson before diving into other forms of chord analysis, so that when any harmony arises you are prepared.