After finishing the first lesson of this program, I've learned new ways to damage and destroy my hearing! http://www.gcaudio.com/resources/howtos/loudness.html
This was a great link to gain some insight as far as knowing the human threshold level of hearing/pain/damge. This makes me want to go back to some shows that I've been to and put some ear plugs in. I remember many mornings after that my ears would ring for a couple days. This was more probably due to me standing in front of the speakers at concert while the bass is melting my face off. SOO much fun, but not the smartest idea.
This guy made learning about decibels interesing.
http://www.youtube.com/watch?v=CAFu7i7nZ18
I really enjoyed reading bout #wavelengths and #harmonics. I knew from my previous guitar playing about harmonics but when playing them digitally, it sounds very different. Kind of reminds of me of laying down hamornies for vocal tracks. I personally feel that certain pieces of a song need harmonies to give more of a fuller sound and powerful presence.