Mosquito buzz told me

Thank you all for your participation in the test for an investigation on auditory ability of different age groups^^. I am happy to have more number of responses than i had expected.
A study shows that highest audible frequency for teenagers is from 16 kHz to 20 kHz, for the age group from 20 to 30 it is 14 kHz to 16 kHz. It gradually lowers but mostly remain at 14 kHz until age 40 when it starts to drop rather sharply something like 12 kHz at 45, 10 kHz at 50, 8 kHz at over 60. But you should note that the test is all about the "average" and includes large individual variation. You do not have to worry if your result is lower than the average.
So it was just for fun to know how we assume it non-existent if we cannot sense it. If it is inaudible we easily take it that the sound does not exist in this world. I myself could not believe that 10 kHz tone was really ringing. I believed the sound was there, simply because my wife told me she caught it. No other way to know it. I trust my wife, so I believe its existence. If I didn't trust her, it would remain nonexistent. Visual version of this parable is also true.
It brought home to me that there should be many many such things in this world I take nonexistent but actually exist. After all we are the most ignorant. Ignorance exists here, but if we cannot feel it, it looks as if it didn't exist.