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#186096 - 10/21/09 10:10 PM Whistles in the woods
NobodySpecial Offline
Member

Registered: 03/03/09
Posts: 197
"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


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#186108 - 10/21/09 11:00 PM Re: Whistles in the woods [Re: NobodySpecial]
scafool Offline
Pooh-Bah

Registered: 12/18/08
Posts: 1534
Loc: Muskoka
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.
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May set off to explore without any sense of direction or how to return.

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#186110 - 10/21/09 11:39 PM Re: Whistles in the woods [Re: scafool]
Michael2 Offline
Journeyman

Registered: 10/07/04
Posts: 54
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."

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#186114 - 10/21/09 11:49 PM Re: Whistles in the woods [Re: Michael2]
NobodySpecial Offline
Member

Registered: 03/03/09
Posts: 197
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.



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#186115 - 10/21/09 11:59 PM Re: Whistles in the woods [Re: NobodySpecial]
Dagny Offline
Pooh-Bah

Registered: 11/25/08
Posts: 1917
Loc: Washington, DC

Interesting, thanks.

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#186117 - 10/22/09 12:09 AM Re: Whistles in the woods [Re: NobodySpecial]
ironraven Offline
Cranky Geek
Carpal Tunnel

Registered: 09/08/05
Posts: 4642
Loc: Vermont
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.
_________________________
-IronRaven

When a man dare not speak without malice for fear of giving insult, that is when truth starts to die. Truth is the truest freedom.

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#186118 - 10/22/09 01:06 AM Re: Whistles in the woods [Re: ironraven]
scafool Offline
Pooh-Bah

Registered: 12/18/08
Posts: 1534
Loc: Muskoka
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.
_________________________
May set off to explore without any sense of direction or how to return.

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#186130 - 10/22/09 02:23 AM Re: Whistles in the woods [Re: scafool]
UpstateTom Offline
Member

Registered: 10/05/09
Posts: 165
Loc: Rens. County, NY
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.

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#186134 - 10/22/09 02:59 AM Re: Whistles in the woods [Re: UpstateTom]
CANOEDOGS Offline
Pooh-Bah

Registered: 02/03/07
Posts: 1852
Loc: MINNESOTA
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..

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#186138 - 10/22/09 03:23 AM Re: Whistles in the woods [Re: scafool]
Russ Offline
Geezer

Registered: 06/02/06
Posts: 5338
Loc: SOCAL
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.
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Better is the Enemy of Good Enough.
Okay, what’s your point??

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