What you're training
The beat and the harmony aren't the same clock. A melody can keep a steady quarter-note pulse while the chord underneath holds still for a whole bar, changes once, or changes on every single beat — three completely different harmonic rhythms hiding under the exact same surface rhythm. This drill isolates that second, slower clock and trains you to track it on its own.
Two levels, one skill
Level 1 asks the basic count: across one bar of four steady beats, how many chords do you actually hear — 1, 2, or 4? Level 2 assumes exactly one change happens somewhere in the bar and asks you to pin it down: did the harmony move on beat 2, beat 3, or beat 4?
Go deeper
How fast harmony really moves — pieces ranked → ranks real pieces by how often their chords actually change, from glacial to frantic. The moment harmonic rhythm gets interrupted → is the other lane of this series — instead of counting how often the harmony changes, it's about the one change that arrives somewhere other than where the ear expects.
Where it fits
Comfortable with chord quality and cadence resolution already? Harmonic rhythm is a different axis entirely — not which chord, but how often the chord itself moves. The full drill ladder has everything else.