Russ,

I also have military flightline-related hearing loss. Mine is actually at higher freqs than the whistles , 1k/3k in one ear, 2k/4k in the other; net loss(in their mind) zero. Add in tinnitus and the only thing missing are the constant voices. I only hear occasional ones; the tin foil in the hat helps.

Opine: I think the whistle noise would be distinctive enough in the outdoors to raise the attention of someone. If you happen to have loss at the three freqs the Fox40 puts out then you won't be able to help.

Good points all the way around.

Further $.02