This is actually a pretty neat mod!
altho i don't intend to use it (I don't use mods in 1.9, only 1.7.10, and i don't play multiplayer in 1.7), I can see many uses for this. Like a server owner, when he/she is just hanging around and a player asks him or her a question. For the dark side like griefers (i'm not a griefer), you can hear people complain about you and what you did XD
it's just me & my hubs that play on our server and whenever i join, i would tell him later, "you never said hi back to me!" and he says, "i don't notice what goes on in chat!" and if he's in a crafting screen or GUI, he can't see what's being said in chat either... so i thought i would look for something audible to let him know that i was talking to him... and this mod was perfect! i would use it in such a way that i would just type his name once to get his attention and then i wouldn't have to keep typing his name over and over.