Imperfect authentic cadence (IAC)
Definition
An imperfect authentic cadence is similar to a perfect authentic cadence but with one or both chords inverted or with additional non-chord tones present. While it still provides some sense of resolution, it may not have as strong of an impact as a perfect authentic cadence.
Analogy
Think of an imperfect authentic cadence as getting close to reaching your destination but taking a detour along the way. You're still moving forward, but there's just a slight twist before you arrive at your final stop.
Related terms
Phrygian Half Cadence: A phrygian half cadence is a type of imperfect authentic cadence that involves the iv (subdominant minor) chord followed by V (dominant) or V7. It creates a unique and somewhat mysterious sound.
Plagal Cadence: As mentioned earlier, a plagal cadence is another type of harmonic progression that provides resolution but with less finality than an authentic cadence. It typically involves the IV (subdominant) chord followed by the I (tonic) chord.
Deceptive Cadence: Just like in perfect authentic cadences, deceptive cadences can also occur within imperfect authentic cadences, adding unexpected twists to the resolution.
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