I like the way Whistlemania/BigPigBlog does their testing using the ears of real SAR folks. I too have high-end frequency hearing loss and it makes a big difference in the real world. Throw in a bit of tinnitus and a whistle tone can be effectively masked. Pulsing the tones helps a lot IMO; it seems that a long tone will get drowned out while short blasts in succession will be picked up, regardless of the tonal frequency.

BTW, I settled on the FOX 40 Sharx, easy to blow (I don't understand "too easy") and a frequency that comes through my ambient background noise.

FWIW