Inna, here's a link that will bring the reality of what is being discussed into the light of day; we are not discussing "frequency" in an absolute sense, but music which incorporates a multitude of frequencies that bring a multitude of harmonics into play at any one given instant.
http://www.psbspeakers.com/articles/The-Frequencies-of-MusicI had a hearing test that proved I have excellent hearing. I also went to a speaker store that generated "straight frequencies" that were not music, and I couldn't hear much over 16K. Now those two facts are in contradiction, because I know I can hear over 16K; therefore the answer must lie in the "harmonics".
If you look at the music chart in the link, you will see that not a lot of music is produced over 16K, but I can tell the difference in tweeters that produce very high frequencies, and those that don't; here again, the answer evidently lies in the "harmonics".
Although I'm an electronic tech who thought he had all answers in the days of Julian Hirsch, and Stereo Review. It was not until I got into the high end, that I discovered I don't have all the answers. For example; how can someone who knows absolutely nothing about electronics, know more than I do about the same subject in regard to speakers?
When it comes to "specifications" and the reality of the way we hear music, those are two different worlds; the "audiophile" who doesn't understand specifications, but knows the reality of the quality of sound that emanates from various speakers, trumps all specifications.
Enjoy the music.