Weeks 5-6 · breath · semi-occluded vocal tract sustain
Sustain through a straw or lip trill. Hold the tone steady for six seconds.
The rule
pass: pitch SD ≤ 25¢ · drift ≤ 6 dB · 6 s
Six seconds on a lip trill or straw. The emerald band is the ±25¢ tolerance — about a quarter-semitone. The green trace stays inside the band; the grey trace is the slow upward walk that fails by the third second. The first 300 ms is greyed out — onset settling is excluded from the standard deviation.
Hear it first
Two reference clips. A clean lip trill sounds almost boring — a steady buzz with no tremor. A drifty one starts the same but the pitch slowly walks. Train the ear before the voice.
What’s happening. Closing the vocal tract at the lips reflects acoustic pressure waves back down onto the folds. That back-pressure cushions each vibration cycle, parking the folds at the low-effort sweet spot automatically. Untrained voices wobble at 40–80¢ SD on a sustained tone; a clean SOVT sustain pulls that down to 10–25¢ without any conscious technique.
Why 25 cents, why six seconds. A semitone is 100 cents. 25¢ ≈ a quarter-semitone — tight enough to expose a register slide but forgiving of jitter. Six seconds is past the 1–2 s easy-hold window where subglottal pressure starts to shift; if you can hold steady that long on a lip trill, the voice itself is balanced, not just held still by luck.
Why this is the foundation. Every sustained-tone task downstream — straight-tone-vibrato, swell-decrescendo, vowel sustains, harmony entry — assumes you can hold a single tone for six seconds without drift. SOVT is the easiest possible configuration. Lock this here and build the vowel-on-pitch skills on top.
Session ahead
5 trials · 6-second hold on lip trill or straw · pitch SD ≤ 25¢ · hit 5 to pass.