I don't own a Sharx, and I didn't find a sound recording of the Sharx on the Web. If someone can provide me either, I can analyze it. Alternatively, someone can do what I did for this post.

On my iMac, I downloaded the freeware "FFT Analyzer", which plots a frequency response of whatever the iMac microphone "hears".

From the sound samples in my previous post, and some whistles I have, I make the peak energy frequencies: (many of these are "multitone" whistles):

• 1700,2300 Hz for the Fastex 72 x 20 x 15 mm and 7g whistle from this Youtube recording
• 2200 Hz for the Acme Thunderer 58.5 (from web recording)
• 2700 Hz for the Storm (mine)
• 2800 Hz for the ACR flat whistle (main tone)(mine)
• 3100 Hz for my "cheap aluminum keychain cylinder REI whistle"(mine)
• 3500 Hz for the Acme Tornado 636 from this web recording.
• 3650 Hz for the Fox Rescue Howler (loudest tone)(mine)
• 4300 Hz for Fox 40 Classic (from web recording)

Since I didn't get the expected 3150 Hz from the Storm, I'm not sure what is going on here. Could be my software/microphone, could be the unit, don't know.

I also found this nice German survival whistle frequency test {link through Google Translate} on the web (with no Storm or Sharx, alas) indicating a peak for the Fox 40 Classic in the 3200-4000 Hz range, a bit different than my results.

It does seem that the Fox frequencies are on the high side, and the NZ results suggest that low frequencies are better for forest penetration.