Do you want to hear the most annoying sound in the world? What about watching the most annoying sound in the world levitate objects? Acoustic levitation takes intense sounds and reflects them back on themselves, producing what's known as a standing wave—a sound wave that seems to kind of vibrate in place, rather than traveling the way a normal wave does.
Ordinary standing waves can be relatively powerful. For example, a standing wave in an air duct can cause dust to collect in a pattern corresponding to the wave's nodes. A standing wave reverberating through a room can cause objects in its path to vibrate. Low-frequency standing waves can also cause people to feel nervous or disoriented -- in some cases, researchers find them in buildings people report to be haunted.
The kind of high-decibel standing waves used in acoustic levitation can actually create pockets of air pressure strong enough that objects inside them can resist the pull of gravity. This particular acoustic levitator was designed by physicist David Deak in 1987, to help NASA mimic the low-gravity environment of the space shuttle, on Earth.
How Stuff Works: How Acoustic Levitation Works
Thumbnail image courtesy Flickr user trialsanderrors via CC
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12 Comments • Add a comment
That's far from the most annoying sound in the world. Neat video though.
I'd call it the invention of minimalist dark ambient using a custom analog synth.
Not actually very similar to zero G. Yes, the object is floating -- but it's resting between "surfaces" created by the pressure waves, so depending on their length and how close it is to the node its surfaces may still be experiencing pressure, and internally it still experiences gravity in the same direction as always.
What this *is* a good test of is the idea of using acoustic levitation to hold material away from container walls in zero-G, eg to perform very-low-contamination reactions. Unfortunately, due to the surface pressure issue, this is *NOT* a great solution for growing ultra-low-flaw crystals, which is one of the proposed commercial uses of space. I've got something I think is a better answer for that purpose, but I've been holding it back in the hope of getting a publishable SF story out of it -- I have the tech, now I need the plot.
Remix! Remix!! Remix!!!
a hairdryer would also do the trick.
Cigar-box ukulele remix!
I'd like to submit this video of a master retarder for "most annoying" sound. On the other hand, I kinda DIG this sound; it carries over many miles of cornfield to my childhood home, and often resulted in some rather freaky mid-sleep wakings, haha.
Sadly, the use of "hump yard" and "retarder" in the title draws so many ridiculous comments-- I can only guess at what these sickos are searching for!
awesome wipes!!!! awesome fonts!
oh the acoustic levitation i guess it's kinda cool... actually kinda boring...
but the video is awesome!
At 0:58 it sounds like a Stuka. You better not turn that thing on near a WW2 vet house.
The two tones played together seem to be the interval distance of a major second
Hmm, I wonder if this would levitate sound?
http://www.youtube.com/watch?v=CrbKn5boVPA#&t=54s
Seriously though, I love the Saturday Morning Science Experiment!
Now star wipe to Flanders brushing his teeth.
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