very true, most caliber and power bullets in flight have a distinctive sound to discerning ears. What is memorable to people not accustomed to gunfire, is the sound made by a ricochet. like in the saturday westerns. And those super high velocity rounds certainly like to ricochet, since it takes a lot to stop them. If trump got nicked by a fragment and heard a whirring sound, I would imagine they will find a divot or point of deflection. It could explain why there was not more damage to the ear if part of the energy was already expended.
Still am not convinced something is not amiss with the narrative so far, but once we get the pieces filled in, I certainly will go where the evidence leads in my thinking about it.