Hacker News Reader

I think the idea was not "breath training" but to reinforce the muscles in the walls of the throat which can relax and obstruct the airway causing apnea.

Humming is a vocal exercise. It engages the vocal cords.

Not sure why you think humming/playing kazoo should be a good exercise for someone who has damage in the vocal cords. E.g. the common medical advice for someone who with a hoarse throat (due to a cold etc) is to let it rest, i.e., refrain from speaking. But I'd be happy to see studies proving that wrong.

The vocal folds are emphatically NOT tougher than other muscles. They are in fact quite fragile and easy to damage compared to other muscles. It is irresponsible of you to post this.