I use the cat toys, the bright color reminds me to take them out, and coloring with a sharpie works well if I want to use them in the show ring. I typically just use them while trail riding, since our trails can get close to the road.
My daughter's mare is very reactive to noise in indoors and the ear plugs really help but I also bought a cd called "Spookless" which is tracks of all kinds of sounds that you would hear at shows such as announcers and metal bleachers, neighing, dogs barking, etc. I played it in the barn first while she was eating then out when we were riding. It really helped her