Well, hearing and perceiving (noticing) are two different things. I suppose everyone "hears" the same things in that the hardware of their cochlea etc. are picking up the same vibrations and producing similar neurological signals. But the 'software' of the brain can be trained to identify things much better than someone off the street might. I don't think this is controversial. An experienced mastering engineer probably has way worse hearing acuity than a typical 12-year-old, because the 12-year-old hasn't been listening to loud music 8 hours a day for 30 years. But the studio engineer can tell which version of a recording has a -1.5dB dip at 200hz because they've had a great deal of training and practice noticing those things. So the engineer "hears" it and the 12-year-old doesn't "hear" it. That's basically all I'm contending here.