Unit 15
Four voices now. Three of them you can already hold from Unit 14. The fourth is the bass, and it's the one holding the harmony up, so the unit starts there and keeps going back to it. Stretched out first, then at real time, then as a full run underneath everything else. The alto and tenor come next, named and pulled out from inside the texture.
Suspensions come back in Lesson 6, and this time they arrive from both directions. The upper voices lean first. Then in Lesson 11 the bass hangs back and suspends under the chord, which sounds nothing like a suspension above it. Lesson 13 puts both in the same piece.
Minor arrives in Lesson 9, in A minor, and brings the shadow register with it. G minor closes the unit. Transposed passes run through most of it.
The arc
Six four-voice pieces, one key each: C, G, F, A minor, D and G minor. Lessons 1 through 5 set the bass under the first two pieces and pull the alto and tenor out from inside. Lessons 6 through 10 add suspensions above, then go to minor and the shadow register. Lessons 11 through 15 hang the bass, put suspensions on both sides at once, and finish with cold runs.
The final is called Off the Loom. Intervals, chords, harmony in context, then a fresh four-voice piece you haven't heard.
An introduction opens the unit. It walks through how a lesson runs and the seven exercises inside it. You identify before, and you audiate after. Six of the lessons end with transposed passes.
Before you buy
It won't let you ride the top line. That's where most ears sit, and four voices only make it worse, because there's more underneath to ignore. The bass is the work here.
It won't keep the suspensions above you. Once the bass starts hanging back, the note you lean on is underneath the chord, and it doesn't sound like the ones you learned in Unit 14.
It won't work without Unit 14. Three voices at tempo is assumed on day one.