The older we get the less able we are to hear certain sounds...CLICK HERE - or simply watch the video I've placed below, and what you find will probably surprise you. Due to a condition called presbycusis there are sounds that only youngsters under 40 can hear. I could actually hear younger than my age. I'm 55 and still heard the 12,000hz - usually only heard by those under 50. See how old your ears are.
-andy