I hope there’ll be bigger surveys on this issue, because the number of participants are not yet so reliable to claim this result so confident from scientific point view.
Anyway I think that you don’t need to be terrifally clever to realize that music can decrease the level of agression in behavior. Simply because any art is a way of self-expression thus it gives a way out to accumulated emotions (no matter possitive or negative ones). Talking about the aggresive behavior, I think it’s important to keep in mind that it can be of different nature and origin (such as emotional tense, lack of attention from adults etc), in other words there can be different causes of such behavior, even when we’re talking about withstanding provocative actions. It’s impossible to find the applicable panacea to all the children, just due to different reasons of this phenomenon.
I’d rather say that aggressive behavior is the consequence and an external expression of psycological problems of this or that particular child. That’s why I believe that it’s more important to investigate the causes of this behavior and deal with them, rather than correct aggresive behavior itself.