Weeks 3-4 · transfer · hum onset transferred into open vowel
Start on a hum. Open into a vowel. Don’t change pitch.
The rule
pass: pitch shift hum → vowel ≤ 35¢
Two seconds of hum, then two seconds of open vowel. The emerald band is the ±35¢ tolerance for pitch shift across the transition. The green trace holds through the hand-off; the grey trace bumps up the moment the lips open — the failure mode is the pitch hitch caused by losing the SOVT back-pressure all at once.
Hear it first
Three clips. A clean transfer sounds like one continuous tone that just changes vowel. A bumpy one has an audible step at the moment the lips part — the pitch jolts. The third is the bumpy one with the slow-mo break exaggerated so the ear can lock onto what it’s listening for.
What’s happening. A hum is a semi-occluded vocal tract — the lips are closed, the soft palate is up, and acoustic pressure reflects back to cushion the folds. Open the lips into /a/ and that back-pressure vanishes; subglottal pressure suddenly drives the folds harder and the pitch ticks up unless the support compensates. Untrained singers shift 50–80¢ on the transition; a trained singer is under 20¢.
Why 35 cents. A shift of 35¢ is roughly a third of a semitone — small enough that the ear treats it as a stable pitch but tight enough that it forces real coordination, not just luck. We compare the median pitch of the last 400 ms of the hum against the first 400ms of the vowel, so brief onset instability isn’t penalized.
Why this is the bridge.SOVT sustains are easy; vowel sustains are hard. This is the lesson that physically transfers the laryngeal balance learned on a hum into a real open vowel. Five-pure-vowels, speech-to-song-transfer, and consonant-vowel-clarity all assume this transition is clean. If you can’t hold pitch when the lips open, the rest never settles.
Session ahead
8 trials · 2 s hum, 2 s vowel · shift ≤ 35¢ · hit 5 to pass.