Vocal Breath is designed to calm the body by working with the vagus nerve, which passes right by the vocal cords. The soft hum on each exhale creates a gentle vibration in the throat and face, and it naturally stretches the out-breath to 10 or 15 seconds.
That long exhale is a big part of why this works: your heart rate slows a little every time you breathe out, and a longer exhale gives it more time to settle. Humming breath like this has been studied for its effect on heart rate variability, a common measure of how easily the body shifts into rest.
It’s especially useful when you feel keyed up, or when you feel flat and shut down and need a gentle way back.