It's always been strange to me how a problem faced by so many players is so rarely dealt with. And that is dealing with distractions. Over the years, how many matches have you lost because something distracted you and you lost your focus? What did you do to solve the problem?
Most likely you just tried to keep your focus in practice matches. That's like developing your loop only by looping in practice matches. It's part of the solution, but you'll develop it a lot faster by doing drills that allow you to focus on that one aspect of your game. Similarly, if you want to work on your focus, find drills that allow you to focus on that one aspect.
I'm going to give one example of how to work on this. When Tiger Woods was developing and practicing his strokes as an up-and-coming junior, his dad would sometimes jingle keys or do other distractions. Tiger learned to focus completely on what he was doing, and the result was nothing could cause him to lose his focus.
You can do the same. It may seem silly, but why not sometimes practice or play practice matches where someone does exactly that - jingles keys, plays distracting music or news, or just talks to you. Your job isn't to just ignore him; that's not the point. Your job is to tune him out so you don't really notice him, so that your entire focus is on what you are doing, like an absent-minded professor who doesn't notice his house is on fire. You need to be so focused and inside yourself that you truly don't pay attention to outside distractions. When you can do that, you'll never have a problem with distractions again.