Considering low whistles or such a super low silver flute and the sound for the listener. I have heard these in real life, the super low flute being played at an exhibition by a very good player (the one they had there was if I remember correctly 5 m long). It was wonderful to the ear, low frequencies are not only wonderful to my ear but they also stimulate the brain in a calming manner.
On the other hand whistles higher than E I personally experience them as a physical attack, this is a serious statement not a “kindly wrapped hint” as I did earlier on, they not only are piercing to my hearing but they make me nervous close to getting agressive. If you have small/er children and want to damage their hearing you should play such high and more often loud keys as much as possible when they are in the room, as a side effect they may dispise whistles in the future, too… . Also if you have animals be it dogs or cats you do not do them any favour in playing such high instruments, too. Both the kids and the pets hearing is much better than yours, they hear frequencies you do not pick up anymore.
Brigitte