As I understand it, there is a tube which goes from the back of the throat to the middle ear. Yawning causes pressure in the tube and this makes the ear drum bend so you don’t hear as well as usual. read more
This is why that brief ‘partial deafness’ occurs when you yawn. Now you know a scientific reason why yawning can be really problematic; especially if you’re listening to an important piece of information that won’t be repeated. read more