I am 30 and was able to hear the 18000Hz tone without a problem (and it's extremely annoying). It's very similar to the sound produced by a CRT that's turned o

I am 30 and was able to hear the 18000Hz tone without a problem (and it's extremely annoying). It's very similar to the sound produced by a CRT that's turned on without video input. Has the "under-20" presumption been empirically tested?