This is the party trick that ends the party. The alarm clock for your siblings that earns you a wedgie. This is THE MOST ANNOYING SOUND IN THE WORLD. It truly is. And it's annoying to difficulty ratio is wonderful. Oh yeah, and it's all because of science.
If you're feeling too un-annoyed today, start with the video to listen in. Then imagine that at about ten times the volume right next to you. And then get a can and do it yourself! You'll be the life of the one-person party you've suddenly created. :)
For nerding out about science, head to the last step.
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Step 1: Nab a Can
Any aluminum can will do! It's the thinness of the aluminum can due to it's strength that will make all the magic. I've found that your standard-shaped 12 oz. can works great. Also, tall ones with the same diameter create an amazing Chewbacca-like noise.
If for whatever reason, you want to nerd out about the ubiquitous nature of aluminum cans throughout the world, this article is a great place to start.
Step 2: Prep That Can
Just two little adjustments to make. Simply flip the tab up, and squeeze your can in half. Push in so the side walls are closer together but not touching. You're ready!
Step 3: The Technique
Getting the resonance takes a bit of practice. You are going to sing a single note directly into the can like in the video. Put your upper lip above the tab and your lower lip below the edge of the can. Go through a range of notes, and you will hear the can suddenly come to life with a metal flicker at one of them. The neat thing is that it's a different note for different shaped cans.
When you find a note for a particular can, hone in on that note. After you find it a couple of times, you'll learn approximately where that note is. And then you'll resonant frequency the funk out of your friends.
Step 4: Science!
Don't worry! The last step could have been the end of this Instructable, you can stop here! You don't need to know the science to annoy! But it helps, and is annoying in its own right. :)
I downloaded a free app called "Tone Generator" where I could generate pure tones from my phone. I placed the phone speaker into the can, and changed the tone until I could feel the can start to vibrate. I found this regular can vibrated around 320 Hz.
This can be a beautiful way to start diving in to the study of waves.
The core idea to the most annoying sound in the world is the resonant frequency.
You see and hear resonanceeverywhere. When you wiggle a particular thing just the right way, it can gain more energy so that it wiggles more. Resonance is the reason that kids can pump their legs on swings to get higher, the reason the Tacoma Bridge fell in 1940, and the idea that opera singers can shatter wine glasses. Poetically, we also talk about something "resonating" with people in the idea that it makes you excited or touches you in some way.
In physics, if some external force oscillates a system at its natural frequency, the amplitude of its waves can increase and increase. In other words, if something wiggles an object, those wiggles can become stronger and stronger. In this case, it is the air pressure from our voice wiggling the can at just the right frequency.
Now acoustic resonance is a part of this that humans have been interested in since forever ago. It is what allows us to project voices, to sing, to harmonize, to play instruments, to make speakers. It is a fascinating world. The can in this case is an example within acoustic resonance of a closed tube, and has a series of equations that you can use to calculate stuff. The neat thing in this is that there are other frequencies that you can resonate the can at. They just were too high for my voice to handle.
Have fun, go annoy, and keep exploring!