Weeks 9-10 · bridge & range · do-re-mi-fa-sol-la-ti-do
Climb an octave and come back down. In tune both directions.
The rule
pass: 6/8 ascent · 2/3
An 8-note staircase up the octave and back. Each step is a discrete pitch held briefly — ±50¢ for ≥ 0.8s — before the next leap. The emerald staircase is the pass. The grey ghost shows the typical untrained miss: mi (the major third) and ti (the leading tone) sit visibly flat — the half-step approaches to do are where ear-confidence collapses.
Hear it first
The full ascending and descending scale played in tune; then the same scale with flat mi and flat ti — the half-steps pulled toward minor. Listen for the brightness of mi and the pull-toward-do tension of ti. Those two notes are the lesson.
What’s happening.A clean Do-Re-Mi-Fa-Sol-La-Ti-Do is the difference between singing “in key” and singing the key. The scale spans an octave (12 semitones, 1200¢) but it contains five whole-steps and two half-steps — and untrained voices reliably miss the half-step intervals (mi-fa and ti-do) by sitting flat. The tightest tolerance is roughly ±50¢, the perceptual threshold for “in tune” on a sustained sung note.
Why both directions, why 8 notes. Descending exposes breath-support weakness; ascending exposes range and register transition. Eight notes covers a full octave, which means you have to hit the octave-do at the top — the same pitch class as where you started, an octave up. That round trip is the most honest scale test there is. The arpeggio cue establishes the key before you sing so you’re not guessing the tonic.
Why this is the capstone.This is the gate to a-cappella resolve-to-tonic, song-from-memory, phrase-transposition, and harmony-over-drone. Most of weeks 11-12 assumes the scale is a known motor pattern — if you’re still guessing scale degrees, the repertoire work will never stabilize.
Session ahead
3 trials · arpeggio + scale cue, then sing the 8-note ascent · each note within ±50¢ held 0.8s · 6/8 to pass a trial · 2/3 to pass the session.