Wow this has turned into a healthly debate- just got back so I'll start here. To the freaking out part- yes I've seen plenty of athletes freak out after missing a shot/kick/etc baseball players react badly at times after striking out in key situations, kickers in NFL have buried their heads in their hands and dropped to the field, soccer players have done the same after missing a penalty shot or an easy one. Every player reacts somehow after a bad miss some contain it internally and some let whatever explode out of them.
With regards to the crowd noise I really think it's a moot point- it just isn't done so whether or not a golfer could adapt it's hard to argue either way. When golf was invented in Scotland but they decided to hurl insults or haggis at each others' head during the backswing or putting- over time, yes I think they would have adapted had that been the common practice and golfers today would be used to it. That's why I think it's a moot point- it's just not done and hasn't been done.
It's not moot because how can you continue to say that Tiger has the greatest mental toughness when he can't deal with something every other althlete has to deal with?