Vocal cord closure is certainly protective in the initial stages of an immersion
accident. This occurs only when the victim is conscious. A person who is
unconscious when they enter the water or who loses consciousness in the water
will not have protective laryngeal reflexes. If consciousness is lost during
static apnea or in an underwater swimming contest, the vocal cords will relax
and will not close in response to inhaled water. Similarly a breath-hold diver
who loses con sciousness will not develop laryngospasm.
The source is "Laryngospasm in breath-hold diving", found in the proceedings of the 2006 Breath-hold diving workshop:
https://www.diversalertnetwork.org/files/UHMS_DAN_2006_Breat...
Vocal cord closure is certainly protective in the initial stages of an immersion accident. This occurs only when the victim is conscious. A person who is unconscious when they enter the water or who loses consciousness in the water will not have protective laryngeal reflexes. If consciousness is lost during static apnea or in an underwater swimming contest, the vocal cords will relax and will not close in response to inhaled water. Similarly a breath-hold diver who loses con sciousness will not develop laryngospasm.