What amazes me is that before I took salsa lessons, each of those instruments was creating sound waves that were actually landing on my eardrums. But I could not hear them. Nor could I distinguish the difference in the beats of the various genres. Nothing about the biology of my eardrum had changed. Only my brain had changed. It had developed a heightened awareness for the beat of the song, and the sound of each individual instrument. Now I can hear things that other people do not hear. But I didn’t suddenly develop super-sonic hearing. I just made a different choice about what was relevant, and my brain is now attuned to it.