Originally Posted By: ireckon
Originally Posted By: ZenEngineer
For a long time now I have wanted to do real world experiments to compare how each model performs in the field. The goal is to order 5-10 models (two of each), separate the family by a known distance (~500m?) and do double-blind testing.
Has anybody done that yet?
That's seems like a good idea. However, an issue I'm seeing is that some whistles may be preferable in certain environments, while others in different environments. For example, perhaps the higher frequency of a Fox 40 will cut through trees better, while a lower frequency of a Storm Whistle will sound louder on the open water. Perhaps a pea is preferable in certain environments. Who knows? Anyway, a comprehensive test in a wide array of different environments would be interesting to read.

{ Note: if planning a lot of testing, consider hearing protection. I've seen referee comments about ear-ringing attributed to whistle use. In an accompanying photo from the "2008 Part 2" test below, the tester was plugging both ears - good idea!}

This first "real-world test" was done by a SAR group in 2006 in the New Zealand Kaimai and Pirongia "bush"(forest) comparing 9 noise-making devices (including yelling).

2006 New Zealand SAR Group Whistle Test (Scroll down to "Whistles"

If you read the full article linked above, you'll see that the forest made a huge difference - the testers said that every one of these whistles were audible at 600+ meters in the open, but as low as 138 meters in the forest.

See the bar chart/table at the link above, but the highlights for me were:
Note that the NZ SAR result for the Storm whistle in forest ( 400 meters = 0.249 miles) is essentially identical to the 402 meters = 1/4 mile claimed by Storm for the Storm whistle in forest on the Storm Whistle FAQ

The Storm FAQ above claims 400 meters in forest, 800 meters over water. Since Storm cites 800 meters over open land for the (quieter) Windstorm, this suggests that range over open land is longest. This would be consistent with the Acme history page, which cites a range of 1 mile for the original Acme whistle in the initial (1883) testing by the London police.

That does highlight the importance of testing for the expected application. The best whistles for forest, desert and sea could well be different, and different frequencies are likely to be absorbed at different rates. Storm thinks their choice of 3150 Hz is particularly effective.

Another factor is the hearing of the listener - in this whistle test, the kids thought the Fox 40 was louder than the Nexus Whistle, the adult thought the Nexus whistle louder than the Fox 40. He speculated it could be due to his hearing loss in the high frequencies.

Another point touched on in other posts is the difficulty of blowing the whistle. If you are going to be blowing a whistle every five minutes in the hopes of being heard, for days, you want something that is easy to blow.

This 2008 Part I 15 whistle test tested measured decibels, not actual humans at range, {Though at the bottom it mentioned an unintended real-world verification of 1/4 mile range through forest} but did use both adult and child volunteers, and includes a rating of how hard the whistle was to blow. This test included the thin ACR (Blast's whistle) and JetScream, but not the Storm.

2008 Whistle Test Part 2 - 12 more items Although the followon test did include the Storm, the flat TOPS KNIVES whistle did best for loudness, at 123.6/117 dB for adult/child. The TOPS whistle also got a "very easy to blow" rating. Between the sound level, ease of blowing, and compactness, that one might be worth another look.

One contender in the 2008 Pt 2 test was an adult human yell: 110 dB try 1, 107 dB try 2, 104 dB try three - affected voice, larygnitis next morning. Get a whistle!


This August 2002 "Whistle Wise" Test in Backpacker Magazine said it included the real world tests you suggest: "search and rescue volunteers whistling systematically in different terrain", but alas the results were summarized to a few qualitative comments. The Storm and Windstorm took first and 2nd place for range, the Acme Thunderer 660 was top for ease of blowing, and they rated the Fox40 Mini well above the Classic Fox40 for ease of blowing by children.

This page at Acme discusses the points of:
  • How hard is the whistle to blow? (Blowrate) - important for endurance, weakened lungs
  • How loud is the whistle? (Blowsound) - certainly helpful in getting it heard
  • What frequencies do the whistle emit? (Blowtone) - likely a key factor in the effects of the "bush vs. open" results above.
This interesting plot at Acme points out the the output level of a whistle can actually decrease as you blow harder, at some levels, then increase as you blow harder yet.

"Shorty" says he tested the Storm, Windstorm, Fox 40, and the full Acme line, and found the Acme Tornado 635 plastic pealesss whistle to be the loudest, but he doesn't describe how he tested them. Acme's description does claim it is their loudest whistle, but comments that it requires hard blowing - not a good feature in a SAR whistle that you may need to blow for hours in a weakened condition.

Here's a five whistle test on Youtube - apparent loudness at 50 yards. The JetScream did best, but none of the other contenders were particularly loud. The Adventure medical Kits flat whistle did not do well here.



Edited by rafowell (02/20/11 05:39 AM)
Edit Reason: Added "in forest" qualifier
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A signal mirror should backup a radio distress signal, like a 406 MHz PLB (ACR PLB) (Ocean Signal PLB)