Siren through your bridge without a break.

What’s happening.Your larynx has two stable vibration modes — what voice teachers call “chest” and “head” register. Between them sits the passaggio: a 3–5 semitone band where the cricothyroid muscle progressively takes over from the thyroarytenoid as pitch rises (or vice versa, descending). If the muscle handoff isn’t coordinated with breath pressure, you get a “crack” — a momentary unvoicing or pitch slip — right in that band.

Why the siren.A siren is a continuous glide between two fixed pitches. It’s the slowest possible way to traverse the passaggio: no consonants, no rhythmic pressure, just one steady airflow through the transition. The slowness lets you feel where the cricothyroid kicks in (or fails to) and adjust subglottal pressure to prevent the break. Doing it on a lip-trill or straw SOVT makes it more forgiving — the back-pressure cushions the folds during the muscle handoff. The 30%-reduction-in-break-severity criterion is calibrated against your own earliest baseline, not a generic target, since passaggio location is voice-specific.

Why this is the bridge. Smooth passaggio access is the gate to mixed voice, belt, head voice belting, and most contemporary Western styles. Vibrato, vowel modification on ascent, and held high notes all assume you can already cross the bridge cleanly. This is the prerequisite that unlocks the upper half of your range.