the problem with azarenka (and every other player who continues her vocalizations until the ball is hit by her opponent) is that she is a cheater.
This is made clear by the fact that she brings her vocalizations up short whenever she nets it.
The fact that she continues vocalizing up to the point that her opponent hits the return shows her intention to interfere with her opponent's focus/concentration, because when that focus/concentration isn't in play (in particular when azarenka, and her ilk, nets it), she willingly stops the vocalization abruptly.
Azarenka and every cheater like her should be fined and fined and fined until they stop using their voices as weapons during a tennis match IMO.