Well, I may be the exception to the human hearing range, (and vison Left 20/12 Right 20/15). Because I have to say that I am over 40 and I can hear well over 20khz. Plus, I work with tile saws and many loud power tools without ear plugs most of the time (because I forget to use them). Although I can hear over 20khz no problem, I don't think that I could make out a song if it was played above 22khz.
Ok it's getting extremely deep here. Most people can hear 20KHZ at 150db, not at test tone levels. That is the purpose for the chamber and the db level.
A mosquito is 571-832hz not even ON the mhz scale yet. No you cannot hear test tones of 20khz at 40 years old, EVEN with concussive/hyper hearing. There are
serious issues with those people, in the real world of noise. I lived with inserts in my ears for 25 years until my mid 40s. I went to several ear specialist
and spoke with them. ONE in 25 million can hear 20khz at birth. NONE in 8 billion can hear it by age 40 with normal test tone db levels.
Using grinders at 40 years of age put your hearing in the 15-16mhz max on a very good day.
The effect of tones on the human body at extreme levels is a whole different thing. 135+ db at 15 hz can eventually cause deadly results. Puff-suits
on dam turbines is limited to under 10-15 minutes and X number of days per year. Your bones crumble.
20khz & 150 db, that's different. That would leave a neighborhood with constant dogs barking and cats fighting though.
You can be trained to HEAR thing with other noises masking the true issue from several hundred feet though. Especially when hydraulics are involved.
Regards
See Snopes for myth busting (et al).
