I think it's probably this. I can actually make this muscle vibrate using some of the same muscles you use when you yawn, but I had no idea that it protects your hearing. I also play music and used to tour in some pretty loud bands. Remarkably I don't have any hearing loss, and actually hear better than many of the high schoolers I teach. (I teach physics so we actually have a section on sound, and we test what frequencies people can hear.) I always felt very lucky that in my mid 40s I'm still hearing well. But I also notice that when things are very loud something seems to "overload" in my ears, and it seems like the sound is being blocked. Maybe I have stronger tympanic tensors?