Okay, have we ever finally decided on the best whistle for survival applications?

I have read that the Fox 40 is hard to hear in a wooded area , although I have also read that younger ears say it is louder because they can hear the higher frequencies.

Just a quick search and at least 4 whistles claim to be the loudest

Fox 40, either the classic or Sonik
Jetscream
Acme T2000
Storm Whistle