At 62, I can easily hear the 12khz, but not the 14khz. So I connected up the wave generator at work to an analog amp w/speakers, and I max out approx 13.1khz.
That doesn't bother me that much for two reasons:
(1) I've played bass guitar since I was 14, and only cared about the low notes.
(2) I don't have to hear the kids' cellphones going off all the time (if they get the mosquito ringtone -- which I strongly encouraqe)
