Is it normal i can filter out high freq sounds like just by thinking about it?

I discovered this ability by yawning. I do this when I am around loud sounds. I find that when I start to yawn I feel a tenseness in my ear canals and I hear a low frequency rumble which effectively blocks out loud high sounds. I can freeze this feeling without actually yawning, and I can do this for several minutes at a time. I am about to turn 30, and this is an ability I have had from a very young age. Anyone else?