Weeks 7-8 · ear · five-note diatonic fragment up and back
Sing five degrees up to Sol and back to Do.
The rule
pass: PAT-B on 8 of 10 (every one of 9 notes ≤ 50¢)
The grey arch is the target contour — Do up to Sol and back down. Each dot is your cents error at that target note; emerald inside ±50¢, grey outside. The classic failure mode is shown at the peak: Sol drifts sharp (the “effort push”) and the descent tracks fine. PAT-B requires every single note in the band — one drift breaks the whole trial.
Hear it first
Two references. A clean pentachord up-and-back at the comfortable tempo. Then a drift example where Sol pushes sharp on the way up and Mi drags flat on the way down — the typical broken arch. Listen to the contrast before you produce.
What’s happening. The major pentachord — Do-Re-Mi-Fa-Sol — covers ~70% of all melodic motion in folk and pop. Up-and-back is the smallest task that exposes directional bias: most untrained singers ascend in tune but go flat coming down (or vice versa). The 9 notes here are 5 distinct pitches but each non-extreme degree is sung twice — once ascending, once descending. PAT-B’s all-or-nothing standard catches the direction-asymmetric failure mode that PAT-A’s per-trial averaging hides.
Why all 9 notes, why ±50¢. Five notes ascending only would let you brace toward Sol and arrive there by effort, then stop. Adding the descent forces you to relax symmetrically — the same tuning relationships in reverse. 50¢ per note is the threshold above which adjacent degrees start to bleed into each other (an Fa that’s +60¢ sounds like a slightly flat Sol). The2.0-second hold per note rules out passing through — you have to commit to each degree, even on the way down.
Why this is the foundation for the diatonic scale. The full octave (one-octave-scale-fragment) is the pentachord plus the upper tetrachord (Sol-La-Ti-Do). If the pentachord can’t hold up-and-back cleanly, extending up to high-Do collapses. Same for descending-five-note-hum (this drill with hum + no rhythm). Lock the pentachord here and the diatonic scale, the tonic-dominant arpeggio, and folk-melody dictation all open up.
Session ahead
10 patterns · 1-3-5-3-1 arpeggio cue then full pentachord up-and-back · each note inside ±50¢ for 2.0s · 8/10 trials with all 9 notes in-band promotes.