In the previous lessons, we learned how to construct, identify, and analyze first inversion triads. One question still remains: when exactly do we use them?
One use of first inversion is to smooth out the bass line.
Look at the example. Notice how the bass line changes direction during the second V chord.
By placing this chord in first inversion, the bass line becomes smoother.
We can also use first inversion when repeating a chord.
In this example, the first two chords are duplicates. A composer may feel that this passage needs more movement.
Instead of altering the top voices, the chord is placed in first inversion.
The diminished triad presents the final use for first inversion.
Early composers did not like using augmented or diminished intervals.
Notice that a root position diminished triad contains a diminished fifth.
The second inversion of the same triad contains an augmented fourth.
Only the first inversion contains no augmented nor diminished intervals.
Because of this, composers prefer first inversion diminished triads.
While root position diminished triads are used occasionally, second inversion is rarely encountered.
It should be noted that the examples presented in this lesson are not strict rules. Sometimes, first inversion is used simply because a composer likes its sound.