Today I was doing some serious detail work on my fence with my jigsaw. I had earplugs because the jigsaw is quite noisy. They're pretty good earplugs, muting the sound dramatically to a distant buzz. But I chanced to yawn, clearing my ears, (which opens up one's Eustacian tubes) and suddenly the sound was dramatically louder! Closing my mouth made virtually no difference as long as my nose was still open, but plugging my nose muted the sound. The noise of the jigsaw was reaching my ears through my nose! Tee hee!