Why is it that when we yawn, at the very same moment we don't hear anything.?

Because when you open your mouth and the ear comes in as negative pressure; the ostacious tube which is a canal connecting middle ear to the pharynx is increase in pressure by air; then pushes the ear drum to out side (slightly) so the sensitivity to sound waves decreases, that is why sometimes we cant hear the sounds while we are yawning.

When you yawn you use muscles that are close to your eardrums. A yawn is designed to increase the amount of oxygen to your brain. So a lot of things are happening at once. It's just like how no-body can keep there eyes open when they sneeze.

When you yawn, you don't hear anything because you ear canals are closed to prevent them from bursting out of your head. that's why you cant hear anything.

It may be pressure and your canals are closed while yawning.

you hear to much of your yawn maybe?

let the medics explain

REFLEX IN THE BRAIN