Our brains edit what we see and hear like a film director's viewfinder. You're probably familiar with this concept every time you take a picture of a distant mountain, seascape, or harvest moon and are disappointed with the outcome. What your vision records is entirely different than what the camera sees. Our brains edit out everything not of interest in the same way a telephoto lens removes extraneous clutter.
The same is true for listening. We often focus on a single aspect of music to the exclusion of everything else. We're so enamored with one aspect or another, like stunning dynamics, that we ignore evidence the channels are reversed.
Another way we use filtering is by suggestion. If I am sharing the listening room my fellow listener might ask if I am hearing this or that. "Did you notice the extended highs?" In fact, I did not, but now that they've been pointed out to me I can focus on them. I may or may not agree with the observation, but I can hone in like a microscope coming into focus.
Some would suggest this selective filtering is at the root of the dreaded Placebo Effect where we are said to hear that which is not real. I would propose it is often this filtering aspect of our ear/eye/brain mechanism at work instead.
Just because someone points out something you hadn't heard before, and then you do, does not mean it wasn't there in the first place.
"Check that out!" helps focus our filters and demonstrates we are more than just mere machines.