Whistles in the woods

"As any searcher knows - sound is one of the most important ways to locate someone. However, environmental factors and type of sound dramatically affect how well we can hear and where the sound appears to be coming from."

http://www.jibc.ca/emergency/Other_Resou...earch_Study.pdf

I have skimmed about 1/2 way through and it seems like an interesting read, even though it spends a more time explaining the science and the method of research than presenting the results so far.

I will comment again after I finish reading and have time to think about what conclusions Bob Manson made.

A couple of interesting points I learned from the article. I've always been concerned that the Coghlan's four-function whistle (whistle, compass, thermometer, magnifying class) was too much of a toy to be a good buy, but it turns out that the whistle part, at least, is actually pretty good and loud - in the top 3 of the 15 tested, and louder than any of the Fox whistles. Also, the Fox micro whistle, which has been part of my EDC due to its convenient small size, ranked among the lowest in carrying distance in a forest. This may be due to its higher pitch:

"From these results, it
is clear that the sounds produced by the sources
with the higher frequencies (pitch) – such as
sources one, four, five, six and twelve – did not
carry as far as those with a similar magnitude,
but lower frequency. It is possible that the
difference is due to the environment’s ability to
absorb different frequencies."

I was a bit surprised how poorly the Fox40 did.
Especially since the guys that did the report (http://www.northshorerescue.com/) hand them out at all their events.

Interesting, thanks.

Interesting, but not really surprising to me. Lower frequency sound always travels further than higher- that is why ancient armies used bugles and horns for local commands, but you had to switch to drums or visual signals for any real distance.

The part that surprised me was that the Fox40 Pro didn't do so well.

OK, I read it.

I was honestly surprised at how well the pea whistles and the Perry did along with the Fox40 Pearl. I really expected the Fox40 Classic to outperform them all except for the Storm

Except for the three bad whistles the rest were all pretty good really. Most of the ranges were over 300 meters (330yds) or roughly 1/5 of a mile.

I am taking a second look at the Fox micro though because I expected them to do better and really don't understand their poor performance. I might change to the Pearl or Perry whistles.

The changes in range depending on the season confused me and I don't understand the reasons for those differences yet. I can't tell if it was because of the snow on the ground absorbing the sound energy or if it was the humidity because they were in a coastal rain forest on a slope near the ocean.

However, the biggest surprise to me was how well the yell carried.
Even though yelling was not as loud as most of the whistles it still carried farther than all of them except the Storm whistle.

This is interesting, but there's data I would like to see. What does the audio output of each whistle look like? What does the background noise look like? I would think it's not the absolute sound that matters, but the signal to noise ratio of the sound of the whistle at the frequency of the whistle.

Also, the data from the distance/SPL chart doesn't make sense to me, except maybe to indicate attenuation. The distance scale is in linear units, but SPL is on a log scale. Without having the actual numbers, the difference in SPL from high to low looks like about 48dB, or 63000:1. Since audio power should diminish with the square of the distance (I think it works like light), that should mean a distance difference of 251:1, but it's not even close to that.

So what's the spectrum of the whistles, spectrum of the background noise, and the loss in the path.

I don't want to discount anyone's hard work, but I don't know how to make any use of this, except to point out that further testing would be interesting.

just about whistles in general,after reading some of the posts here i added one to my dog walking-hiking gear.trying to explain where i was in some Mississippi backwater island,injured,on a cell phone would not be easy..blowing a whistle would help find me after phoning for help..as in--i'm sort of down by the third sandbar island but off in the woods by a creek--someplace..the story of the lady trapped next to a river who could hear voices but not get anyone's attention clinched it for me..

Looking at the frequency of the Fox 40's, the reason why they don't seem to be very effective to me is more apparent. That narrow frequency is in a range that I've lost due to hearing damage (turbine engines, et al).

One aspect to these tests that is missed is modulation of the whistles/tones. The sound may need to overcome background noises in the same frequency (like my tinnitus) and one way to do that might be to modulate the tones.

Yes, SAR stories are full of people where it took hours to fin somebody once the rescuers were within a few 100m of the victim.

http://www.northshorerescue.com/blog/ (these are the people that did the report)

That might explain why the pea whistles did so much better than I expected too.
In the same vein, does anybody have an idea if the Fox Pearl is enough different but still close enough on its two frequencies to form a beat frequency between them?

Interesting study, thanks for posting it.

I carry a Storm on my off-road m/c kit & will attest that it is loud enough to hurt.
I used it recently to catch the attention of other riders going by. They could hear it 50-m away while wearing helmets & riding motorcycles at 50-kph. Some even heard it through ear-plugs.

The Storm is kind of big & clunky, so most of our other kits (wife, son, car, air-travel, etc) have a mix of Fox40 Pearls & Minis.
My own very unscientific comparison between these Fox40 & the Storm matches the report - the Storm is a lot louder.
There is a huge difference between 90dB & 110dB.

I've tried using whistles to signal in the woods a time or two. Was shocked at how the sound did NOT carry!

(Still better than trying to shout for hours though)

Fox40 has some interesting new designs, and a nice selection of marine safety gear.

I especially like seeing Don Cherry, but most where I live wouldn't know who he is.

I always wondered where Don Cherry got his suits, but what really used to get me was how tall the collars on his shirts were.

We used Fox40 Classics for the riggers swamping the cranes. They were loud enough to be heard over the compressors and motors on site for far enough to alert anybody in range of a lift.

That is why the report rating them as no better than the pea whistles surprised me.

Hearing loss from use of the whistles, esp. if there is a need to use for some hours, is sometimes avoidable. I keep ear plugs at home and in my car kits for this and other times they are needed. Perhaps a set should go in the BOB, as well. They're certainly cheap enough.

The study certainly proved one thing. Have a whistle.

I haven't been able to open the link, so I'll remain skeptical...

Whistles are a categorie of audible signal that I can't remember being useful for any of the searches I've been on, but that is not quite a scientific study. I can remember three times when I located the person by shouting: once on a clear day over a mountainside, once in a snowstorm in a wooded/rocky area at daybreak and once in the middle of the night... yelling every so often..."Jeeeeessssssseeeeeeeeeeeee...Jeeeeessssssseeeeeeeeeeeee"...the teen was sleeping soundly in the heavy bush about 3 feet off the trail and jumped straight up when he heard my yell...scared the crap out of me...

Oh, one more came to mind. Middle of the night in farmland, two youngsters went out to play after school and never returned. Introduced myself over the loudspeaker and assured them they weren't in trouble (youngsters will hide from adults when lost, believing they will catch hell when found). I told them their parents were worried and told them they needed to help us find them by making noise, and instructed them to "make noise...Now!". They started to yell, which sounded a lot like a herd of sheep in the night... the firemen who had been combing the area were now able to find them... the only part visible was their faces... they had tried to cross an "empty" irrigation canal and had sunk in the mud to the point where less than half of their head remained clear... The mud is a tremendous force and it took several adults several minutes, probably close to half an hour, to keep the kids from sinking more and to free them from the muck.
If the parents had waited another hour to call, probably would have never known what had happened to them.


Gunshots (into a safe target) travel very well, but echo so much it creates pin-pointing problems at a distance.

I spent a couple of days this week giving out the mini Fox-40's to AF guys in the SAR and air crew survial business. I heard from several that the pea-less designs do have the advantage in working in extreme cold environments. Also that the fact that the Fox-40 sound is "ugly" makes it easier to hear above the background noise. One tech sgt. mentioned that she uses one I gave her last year to get everybody's attention in the machine shop in which she works.I also gave them out highlighting their usefulness as a personal protection tool.

Can't comment on the study's methodology but as someone else said having one is better than not having one.

Andy

Well yeah, the darn pea in the pea whistles used to freeze up and then they would be hard to get any sound out of at all.
The metal ones would freeze to your lip too if you were not careful.
I remember carrying the metal pea whistles in my inside parka pockets so they would stay warm enough to work and not tear pieces of my lip off.
The plastic Fox whistles were a huge improvement.

Interesting, I have always wondered why survival whistles have become so high pitched over resent years. Especially as it has been know for around 100 years that low pitched sound travels a lot further than high pitched.

This was shown in a very practical test when researching the improvements of nautical sound signals and foghorns. I don't remember the chaps name but he had a piano placed on a beach and different notes played whilst he sat in a rowing boat seeing which note was heard the furthest. He reported that the low notes could be heard the furthest and this was adopted for use in foghorns.

You can generate a lot more audio power at higher frequencies in a smaller package. (That's why double base players are never popular in a marching band).

I guess a Fox40 mini is easier to carry than a basoon!
A high pitched noise probably also stands out better against any background, the sea in fog is relatively quiet.

Although sound travels better in a moist atmosphere, fog is to dense so absorbs sounds, especially high pitched sounds.

I have lived by the sea all my life and within hearing distance of foghorns including the Portsmouth harbour entrance marker horn and the Bristol Channel navigation horn which can be heard at 46 mile minimum distance. Just because it is foggy it does mean it is relatively quiet, the sound is absorbed so it is perceived as being quieter, the foghorn has to be able to cut through that effect.

If you read the article and other articles about sound waves you will understand that long soundwaves travel around and often through obstacles far better than short soundwaves this point to the fact that low frequency sound is less disturbed and distorted by the environment than high frequency sound allowing it to travel further. This can be heard on wide band radio.

I recognise that to produce low frequency sound you need a larger chamber than high frequency sound. My point is manufacturers are kidding themselves by making louder whistles with higher frequency sounds instead of increasing the efficiency of lower frequency whistles. The fact is the manufactures are going against hard scientific fact and misleading people with their sales pitch in the process.

My original post was reflecting on why manufacturers feel the need to do this. the reason is the average person does not understand the process of sound so they perceive that a loud high pitched ear bleeding sound is more effective when they blow a whistle than one with a lower pitched sound, using our own failings in hearing to mislead use, probably through the lack of understanding, of which is the best sound.

A well researched and engineered whistle at 70dB would be far better than one at 105dB. This is borne out by the human voice compared to the storm whistle.

Fascinating article.

I found it very interesting that the Coghlan's whistle I bought "until I get a better one" turns out to be one of the best performers. Guess I won't be replacing it after all.

(I also have a Storm in my GHB, and the Fox Micro in the AMK PSK in the GHB.)

Also interesting that the metal survival whistle that came with another PSK I was given is the lowest performer of the bunch. Well, I put it on my keychain for more mundane whistling, so that's not a problem.

This was certainly an interesting article but it failed to recognise one simple fact.

The study did find that louder whistles can be heard at greater distances.

But the study failed to take into account that louder whistles take more effort by the person producing the puff to make that louder sound.

In a search, the person blowing the whistle will tire more quickly whilst blowing the louder whistle than the quieter one hence reducing the probability of a search party hearing the whistle. This was not factored into the results.

I'm sure thats true.
My point was that a higher pitched sound might attract more attention against background noise than a lower one.

I suspect that whistles are now so common that any other sound wouldn't work as well. If I heard a whistle in the woods I would assume that somebody needed help whereas an air horn I would guess was some construction work, forestry etc.

Interesting article. You would think that someone might come up with different whistles that would be suitable for different situations, rescue for one, job site for another, instead of one-size-fits-all sort of thing. Like flashlights.

It appeared that they measured the distance of the sound in feet, if I was reading it correctly. Elephants communicate with infrasonic rumbles that are so low that humans can't always hear them even when they're nearby, but other elephants will pick up the 'message' over two miles away.

Sue

Very true Susan, if i remember correctly forest elephants in fact communicate much further than two miles using this method.

In the jungle a whistle is next to useless. The best way to communicate over long distance is to drum on the buttress of the silk cotton tree. This gives of a deep low frequency sound that cuts through the jungle for quite considerable distances.

Another problem with high frequency sound is because it has such a short wavelength it is reflected of of obstacles a lot more so although it might stand out over other noises a little bit better it is a lot harder to determine the direction it comes from. we experience this when we first hear emergency vehicle sirens.

Great to have actual measurements of the practical range of my whistles.... (or voice for that matter, I have a pretty strong voice, but I can't shout at maximum for more than just two minutes before I have to lower the volume or go completely hoarse).


From their charts I deduce that I shouldn't expect people to notice my whistle at 500 meters (unless perhaps in favorable conditions) ... but at 200 meters there's a pretty good chance they will notice. In my book, that's great to know.


200 meters doesn't seem as much, but it is in fact quite some distance in the woods. Lots of people can be in a 200 meter (600 feet) radius and you won't even notice them. If there's a trail within 200 meters, people on that trail should be able to hear you.


To increase that range - does anyone have ideas of how to improvise low frequency sound devices? A makeshift drum is obvious, but perhaps there is some other techniques for squeezing low/medium frequency sounds out of some garbage or equipment? I don't think a drum will attract much attention beyond "curse that hippie, he can't even play". Hopefully, if you bang long enough someone will turn up to tell you to keep quiet.

So I'll be looking for bongo drums to carabiner to my backpack.

This suggests a thread on other noisemakers in case you don't have a whistle, or in addition to a whistle.

Problem solved:

http://www.latestbuy.com.au/electronic-drum-kit-shirt.html

Electronic Bongo Drum T-Shirt

US $56.35

The Electronic Bongo Drum T-Shirt is a touch sensitive drum T-shirt with built-in speaker, so you can belt out a rampant rhythm that sounds just like the real thing.

Another problem with any signalling device is that some people don't realise its use as such.

Many years ago i was on Dartmoor in the south of England and heard a whistle blows. It was right on the edge of my hearing so although i could hear it sporadically i could not get a fix on its whereabouts. I stopped and listened. whilst doing so a large walking party that was following me on the same route neared and i asked if they had heard whistle blasts they said no. Just then we all heard the whistle blast and people in the group said oh there it is and all pointed in different directions. I cupped my hands over my ears and determined the correct direction and started walking in that direction, saying i am going to have a look as someone was in trouble. It was only then that some in the group actually recognised the significance of the whistle blasts and a debate started on whether they should carry on on join me in looking for a casualty. the thing that struck me was the group looked quite experienced, had the right kit and everyone of them was carrying a whistle attached to different parts of their clothing but it still did not register with them that whistle blasts was from someone in distress.

Something i have carried and used to get the attention of groups spread out over large areas is a horn, the type you used to see on old cars, a horn with a rubber bulb that you squeeze. Modern ones of these are small, strong and light. I first came aware of them seeing demolition teams use them to warn that they were about to detonate when dropping chimneys and other structures. the cave rescue guys at my caving club used these to communicate in caves too. I must replace my horn as it went walkies.

A fun alternative a friend of mine has used at ski resorts is a Duck Call.

To others in your party it would be uniquely recognizable.
Maybe not so much as a distress signal ..... unless you quack out an S O S.

Hi all.
Horns are for low frequency/ further reach in heavily wooded areas (i.e. jungle).
I have a few of these cheap sports airhorn thingies.
I got them off evilbay .

If you want to make your own, here's how:

http://science.discovery.com/brink/kip-kay/air-horn/air-horn.html

Pharaoh.

try "garrettwade.com" for odd tools.check out the whistle section.
Metro police whistle's--hand held fog horns..very spendy for some of these items..

The article has several important implications including but not limited to:
1) Pick the right whistle for the right season and terrain.
2) Not all whistles are created equal (no surprise there, eh?).
3) There may be places where others cannot hear your signal - be aware of them.
4) More research is needed to identify the whistles that perform best during a specified season and on specified terrain. For instance there is nothing in this article about how the whistles perform on open seas.

Perhaps Doug has some input here. Could this be a job for the folks at ETS?

I was not that surprised on some of the results. For instance I have noticed for a while that my supposedly cheapie silver Metal Pea whistle sounded a lot louder than the Fox-40 Rescue Howler in my PSP. That said there are still many good reasons to stick with the Fox-40 as it is a pealess design that won't freeze to my lips in extreme cold.

Of course the most important lesson here is to be aware of the capabilities and limitations of our equipment and ourselves.