grew up in an era where that wasn't possible, and haven't gotten into the habit. It's not what's relevant to me. I want to suck up the energy of the shiai, and make sure I'm not missing a call to the tatami. I like watching what my opponents are doing with other opponents, so I can see what their style is, what their tokui waza is, and what works against them. Shutting out the rest of the world isn't attractive to me.