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.

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!

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29 Comments

AengusR

Tip 2 years ago on Step 4

Once you try aluminium why not go to next level and shatter a wine glass .... https://www.youtube.com/watch?v=X6iJ0hPpGec

Laral

4 years ago

I just revisited this page because I want to make one of these to scare away pigeons. I looked at the spectra of the 3 you show in the video. The first two show a clear harmonic relationship to a fundamental frequency. The last one is a mess, with a few harmonics in the lower frequencies, fading into an indistinct blur of overtones, which is what I expected of all of them. Interesting.

Laral

7 years ago

The sound is as annoying as the (complete lack of) 'science'. Resonance, yahhh…, and…?

Laral

Reply 7 years ago

I see you listed the science as a separate part. I guess you can't do any better than that. Please excuse me for ignoring it. That's MY fault.

And, yes, amplification by resonance phenomena is an amazing concept with remarkable results. One man dedicated his entire career to resonance phenomena--electrical, mechanical, atmospheric… That man was Nikola Tesla. You may know about his so-called 'earthquake machine' (not the name he gave it), a mechanical device that could cause an entire building to vibrate at its natural resonant frequency, just like the Tacoma Narrows Bridge that you mentioned. His amazing high frequency, high voltage, 'Tesla coils' were basically resonant transformers.

I should clarify what I said about the modes of the can. When I said frequency, I meant wavelength. It should be "Resonance in a closed tube occurs when the WAVELENGTH of the injected sound wave is equal to the FUNDAMENTAL WAVELENGTH of the tube, which is dependent on the physical length of the tube, and is equal to twice the length of the tube, or a half-multiple (.5, 1, 1.5, …) thereof." According to what I read in 'Vibrations and Waves' - A.P. French, these are the harmonics of a tube that is OPEN at both ends, in which case there is an antinode (maximum) at each end. He goes on to say "It may also be noted that a tube with both ends closed has the same set of natural frequencies as one with both ends open, although it differs from it by an interchange of the positions of nodes and antinodes." So in this case, the closed ends support a node (minimum) at each end. The can is approximately a tube that is closed at both ends.

As to your comment "that the resonant frequency or "natural frequency" of a closed tube will also be dependent on its material or its "mass per unit length" given as p in most resonant frequency equations." It is the air that is vibrating in this case, not the enclosing medium. You're thinking of the longitudinal vibration of a rod or tube in which the material itself is vibrating. In that case there is a significant dependency on the linear density, usually given by RHO. With air, there is a dependency on the volumetric density, the mass per unit volume, of the air itself, also given by RHO, and on the air pressure, but since these are constant at STP, it can be said that the resonant wavelength is dependent on (proportional to) the length of the tube. That is the primary first-order dependency that is within the scope of this Instructable.