It’s like informing someone who thinks they can see microwaves and x-rays that human vision is limited to red through violet wave lengths. It’s like telling someone who claims they can run 100 mph that no human can run faster than 23-25 mph. There is nothing extraordinary about your stereo or the stereos of other audiophiles or your hearing acuity or the hearing acuity of other audiophiles that is unknown, unresearched or magical. Human hearing thresholds are not mysterious unknown quantities.
It almost sounds like you're living with absolute certainty that we know everything there is to know. For example and let us assume that you can't hear 20khz or above. Now when you play a 21khz and 22khz simultaneously there is a possibility of a doppler pattern that occurs deriving a 1khz summing signal to your 1khz band, which you will definitely hear. It ain't all that straightforward dude..
There are various phenomena observed in nature for which we know how provide some type of empirical solution. We could simulate some other phenomena with physics models and so on, but, we can't always validate with measurements. We don't have the capability to measure everything or even know what to measure. There are very known limits to measurement instrumentation or even the design of certain types of experiments. There are all kinds of PhDs working 16 hour days because of the above mentioned. If they all take a pompous arrogant stance that "what they do not know shall not exist!", that would be very dumb.