Opening a high-end shop in 1973 and learning by LISTENING to the many, many products we carried--over 75 different manufacturers--crazy bookkeeping--and then spending my time LISTENING to everything when we closed the doors for the day.
I also happened to have a number of actual musical instruments that, while I am no musician, I could play well enough to HEAR what they sounded like live.
Then, I continued to go to many concerts of ALL KINDS of music (except opera--there wasn't any down here back then, and frankly, I was not really interested in it enough to find it somewhere else--mea culpa.)
Anyway, I changed my opinions on almost everything by LISTENING and focusing on the specific sounds of instruments and learning to "separate" them in my head while doing so. My time learning to play guitar iin college by listening to guitar parts "only" helped me with this. It is not "scientific" any more than my playing my various instruments "live" was, but it helped.
Finally, I played in many bands when younger and worked with actual musicians who wanted a specific "sound" from their instruments on various songs, so I learned that all musical instruments could produce many different sounds.
Complicated, but the Mayorga Direct-to-Disc pressings were also helpful in all this.
SO, it is a combination of many elements that go into this hobby that result in "learning" to listen to music.
Finally, I taught a "Listening Skills" class at my job (large computer company) after I sold the store, and let me tell you, teaching engineers and programmers and managers to "listen" --especially to each other!--is much harder than determining if the drums were mic'ed correctly on a specific recording!
We always said that "listening" is the hardest skill to master. I believe today's world illustrates that better than anything I could post.
Cheers!