<Snipped quote by XxFellsingxX>
Babies tend to babble before they speak. So...Babbling in Common & Primordial? Probably still just as terrifying.
Also consider the dialect of primordial based on which elemental plane. It's already supposed to be a harsh language. Terran, dialect of the dao and residents of the plane of earth, is probably a bit more guttural.
Not sure about the others. Maybe more nasally for air elemental plane denizens. Flowy but deep resonances for water elemental plane folk. For those of the plane of fire in not sure.