I've just 3d-printed what's supposed to be an ear-shatteringly loud emergency whistle (120 dB at one meter). However, it's apparently somewhat sensitive to printing conditions, because some people report their whistle doesn't make any sound at all when blown. Clearly, I need to test mine before I encounter an emergency situation.

How can I test my whistle without causing people to call Search & Rescue (or the police)?

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    Just blow it. It's not like it's taboo to blow a whistle. – ShemSeger Nov 7 at 6:14
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    In India, if you blew a whistle, no one would care. At the worst, people would smack you for making them deaf. So I guess it depends on which geography you are from :) – Ricketyship Nov 7 at 6:24
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    120dB is not that loud. Unless your neighbours are actually more like "flatmates" I don't think at mid day test @ 120 dB is going to upset anyone. – Stian Yttervik Nov 7 at 7:44
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    @Mark I would never think to call the police to report a loud noise that lasted for a couple of seconds and did not repeat. – Nuclear Wang Nov 7 at 14:12
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    In the UK stand outside the police station and blow - if they turn up within 3 days it probably works. – Darren Bartrup-Cook Nov 7 at 15:42

You just need a place where blowing a whistle wouldn't be out of the ordinary.

Perhaps a city soccer/football field would work as people blow whistles there. Or if you could find an outdoor area where you know there won't be people around within hearing distance.

A distress signal is given in 3s, so one blast shouldn't be a problem.

Do note that you should definitely be using ear protection, this calculator says that if its 120 decibels at one meter then it would be 140 decibels at 4 inches and 140 decibels is more than enough to cause pain and puts you at risk of permanent hearing damage.

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    International mountain distress signal is 6 blasts, repeated every minute. 3 blasts, repeated at one-minute intervals is the response from rescuers. But yes, it's worth avoiding something that might be mistaken for either. – Toby Speight Nov 7 at 15:43
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    @TobySpeight That is interesting and good to know. Can you provide any citations so we can see how common that usage is? As it stands, I have not heard of that. I have heard that 3 does not always mean "help!" in every system, but that it usually does, and that people should make noises in groups of 3 to try to signal for help. That is the teaching I have seen most prevalent. – Aaron Nov 7 at 16:49
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    @Aaron, I'd never heard of using groups of three (everyone knows it's six blasts every one minute), but when I went for a reference, I discovered that there are in fact places where the distress signal is only three at a time. Which is confusing. It seems there's no way in those places to distinguish an acknowledgement and another person in distress! – Toby Speight Nov 7 at 16:55
  • The reason for the three signals is from Morse code for SOS. en.wikipedia.org/wiki/SOS. S is three short blasts, and O is three long. – Cullub Nov 7 at 21:31

Very indoors, shut up tight, and at a suitable time of day.

If you live in a house (as opposed to a flat), and it has reasonably good insulation and tight-fitting windows, the high-pitched sound of a whistle will be significantly attenuated. The noise level is comparable to a burglar/car alarm siren, and they're fairly common. If you've ever heard an inside siren (only) going off from outside you'll get an idea of the attenuation.

Then if possible find a room or closet with no outside walls or windows, go in and shut the door. I'd use my downstairs cloakroom or even the cupboard under the stairs (the former has an extractor vent to outside which I know let's sound in). In such a confined space it's even more important to wear ear protection. Then a quick blow should be enough. I suggest rinsing it out in a cup of water and testing again while you're there, to ensure it works in the wet.

If your house a shares a wall with neighbours, try to do it while they're out. By this point, people in their own homes will barely notice, and it shouldn't be annoying to people outside, except right outside your house. You should still aim for a time when you won't disturb people - in the middle of the day presumably

If you're still worried, wait for lots of background noise - perhaps when the neighbours are cutting their grass. This will mask the sound as their nose is emitted outside, will make it less annoying as you're adding little to an existing noise, and will make the location of the source almost impossible to detect (a short blast remember).

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    Just imagining family members looking at me going into a closet to blow a whistle :P – Ricketyship Nov 7 at 7:36
  • @Ricketyship better to warn them! But most outdoor activities get those looks at some point either during the activity or while sorting out kit. Combining it with a game of hide and seek would be cruel but effective – Chris H Nov 7 at 8:07
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    An indoor gun range would let you make an unlimited amount of noise if you wanted to do it more than once, you would probably just need to ask nicely first as it would be a strange request. – Charlie Brumbaugh Nov 7 at 17:12
  • @Charlie if such things exist and are reasonably accessible where you live. We don't have a lot here in the UK. You'd want permission too. – Chris H Nov 7 at 17:19
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    @DavidRicherby I'm inclined to agree but the OP is obviously worried about it. When I had a particularly fearful neighbour I would have been too – Chris H Nov 7 at 18:01

It doesn't matter. Blowing a whistle is not an emergency signal: emergency signals have a certain sequence. Be sure to use your hands to close your ears (index fingers pressing ear canals closed). If the whistle works, you'll still notice.

Frankly, outdoor shops have working emergency whistles probably cheaper than what your printer materials cost. So there is not much of a point in printing one.

  • I seriously doubt that I can buy an equivalent whistle for less than $0.36. – Mark Nov 8 at 20:35

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