The OP is only half right. Yes, the brain is the CPU (Central Processing Unit) that processes and defines what the ears send to it. That being said, how many of us get routine audiologic evaluations? How many of us routinely clean our passive receptors? Come on now, all you old audiophile farts out there? When was the last time you had your hearing evaluated or Debroxed your ears? Are you really convinced your hearing acuity is as sharp today as it was when you were young whipper snappers? For that matter, how many professional audiophile reviewers get regular/routine audiologic evaluations? Perhaps this little tidbit of CV should be listed or documented right before their personal impressions and specifications & measurements in reviews?
As for the requirement of decades or even years of training to teach our ears and/or brain to truly comprehend what they are sensing, well, I'm sure that kind of training investment is required for competently reading or deciphering XRAY, MRI, EKG, EEG and other such telemetry. However, for music appreciation, I think the old adage applies: "You don't have to know much about art to know what you like."