Players yelling at opponents taking shots...

[MREUROREF]

I had a game last week where B1 would yell at A1 while he attempted shot. The first time I shifted my eyes out of AOR when i first heard it. The second time the guy had beat him on the break, so I felt it was out of frustration, but the third time we gave him a warning for USL Conduct. Does anyone know if the rule book in/directly address this distraction tactic. I've seen some yell at the freethrower on the line, could this be construed as a lane violation? I've seen one of the threads before that covered players waving their hands while in the lane during freethrows that touch on it briefly, but i was wondering would this be a violation or penalized like obstructing player view? (Technical)