Reactive Aggression in Wheaten Terrier

We're looking for some help in dealing with , what we call, "reactive aggression" in our Soft Coated Wheaten Terrier.  "Kellen" is a two year old female, living in a household with eight other female dogs.   She is the third largest in size overall.    For example, if another dog should "cry or whine" , Kellen will attack.   I doesn't happen all of the time, but when it does happen , it seems inappropriate to us, because neither dog has growled.   Kellen WILL attack one of the other dogs if they growl to protect a treat or a toy that they have.   We feed supper to all the dogs at one time, in one room , without any aggression.  When we feed the dogs, there is NEVER a problem with aggression in Kellen or the other dogs.   We can understand the "protecting" of a treat or toy, but we don't understand why Kellen would respond aggressively to a "cry or whine" that is not even directed toward her.    If anyone has any insight or suggestions, we would appreciate your help.   Thanks !