"Hear" and "hearing" are 2 separate things......many young umpires have what was called "rabbit ears"....that is hearing and taking offense to every negative comment made about them or the calls they have made...."hearing" and letting that affect you negatively only pulls you off your game....it hurts your concentration and your ability to call an effective game.....
Those umpires who cant get past this in their training will cite this as the reason they gave up umpiring......hassle from fans......you will not umpire long nor successfully if you do not get over "hearing" the fans.....
we train umpires to "hear" what goes on around them, but to confine themselves to the area that the rule book gives them jurisdiction over. (confines of the field). its why you will hear so much about getting trained here.......
If you make the right rule call, any negative partisan comments dont mean a thing....if you are in the right position to make a call, comments from people hundreds of feet away dont concern you......if you make a judgment call based on the best view you had of the play, within the most common 2 man system, negative comments dont carry any sting.......
Understanding that baseball is a passionate game, and some that watch it and have an interest in who wins, will put on to the umpires, a unfair responsiblity for the loss of thier team.....in reality as I posted above, most all of us have no interest at all who wins......
let me give you some example from my experience...
Had a woman berate me from the stands for 2 innings because i called an out at 2nd without the player being tagged......(it was a force play..no tag needed)
Had a dad ask me why I wouldnt call the high pitch a strike for his son.....(um....it was high?)
Had a woman follow me to my car to yell at me that I had called her son out because I didnt like him...(I had to ask her which team her son played for, then what position he played since i had no idea who she was talking about)
I'll bet you all 3 of those went home thinking I had it in for them and "got even" , which couldnt be farther from the truth.....