I guess this also begs the question, how much of that high frequency content is in what each of us likes to listen to? Looks like I'm going to have break out the mic and start watching the RTA for everything
I agree about frequency extension of hearing and how it does not make you a good listener. Not much musical energy above 10Khz anyways. The best listeners are those who have a natural gift or have trained long and hard themselves to really LISTEN and to get into a zone while listening in hearing all the wonder of full frequency and depth recorded music or live music for that matter. Sadly we have a gen or two of a lot of now casual listeners and music is only a background or such with say just an ipod or similar. They have not bothered to really learn how to listen and to really enjoy what great music be it live or recorded can sound like. IMO its a sad loss of pleasure for them.
To get some perspective, the fundamental tone of the highest note on a piano is at
4186.01Hz. (My guess is, that will surprise many people who are interested in audio gear, who would probably expect it to be higher.)
Here are the fundamental ranges of quite a few instruments:
Of course, there are also overtones, but you get the main note for most things just hearing up to 5kHz. The overtones go up beyond what is humanly audible in some cases, so even the upper reaches of human hearing make a difference for some instruments.
But generally, a 10kHz upper limit has only a slight affect on most music (that is, for those capable of hearing higher). Ironically, to sound natural, common noises have been found to need the highest frequencies more than music typically does to sound fairly natural; see:
http://www3.alcatel-lucent.com/bstj/vol10-1931/articles/bstj10-4-616.pdf
