What it is
The vertical position of the larynx (the thyroid cartilage / Adam’s apple) in the neck. It rises when you swallow and drops when you yawn. While phonating, the ideal is a relatively stable, non-rising position — a rising larynx usually means the outer neck muscles are “helping”, and squeezing follows.
Where it comes from
Acoustically it is inferred from features such as the correlation between F0 and F1 (a rising larynx lifts the formants as a whole), combined with visual comparison against the side profile. SonaLab’s Larynx Position monitor gives a continuous relative-position curve.
How to read it
Read the trend, not the absolute value: a slow upward slide (especially into the high notes) is a compensation signal; healthy gear-changing allows minor adjustments but no sudden jumps.