[Ben Krasnow’s] latest project will be good for anyone who wants a complicated way to cheat on a test. He’s managed to squeeze a tiny FM radio receiver into a ballpoint pen. He also built his own bone conduction microphone to make covert listening possible. The FM radio receiver is nothing too special. It’s just an off the shelf receiver that is small enough to fit into a fatter pen. The real trick is to figure out a way to listen to the radio in a way that others won’t notice. That’s where the bone conduction microphone comes in.
A normal speaker will vibrate, changing the air pressure around us. When those changes reach our ear drums, we hear sound. A bone conduction mic takes another approach. This type of microphone must be pressed up against a bone in your skull, in this case the teeth. The speaker then vibrates against the jaw and radiates up to the cochlea in the ear. The result is a speaker that is extremely quiet unless it is pressed against your face.
Building the bone conduction mic was pretty simple. [Ben] started with a typical disk-shaped piezoelectric transducer. These devices expand and contract when an alternating current is passed through them at a high enough voltage. He cut the disk into a rectangular shape so that it would fit inside of the clicker on the ballpoint pen. He then encased it in a cylinder of epoxy.
The transducer requires a much higher voltage audio signal than the litter radio normally puts out. To remedy this problem, [Ben] wired up a small impedance matching transformer to increase the voltage. With everything in place, all [Ben] has to do to listen to the radio is chew on the end of his pen. While this technology might help a cheater pass an exam, [Ben] also notes that a less nefarious use of this technology might be to place the speaker inside of the mouthpiece of a CamelBak. This would allow a hiker to listen to music without blocking out the surrounding noise.
Bone conduction /speaker/, not microphone.
Good writers are hard to find.
Almost anything that acts as a speaker can also act as a microphone, piezo transducers included.
Sure, but I think he’s pointing out a mistake in the write up as it’s somehow inconsistent with the use of “microphone”, and “speaker”.
My point was that it was technically correct, whether or not it was appropriate in that context.
Then again, listening from a microphone just sounds silly.
It can be used as both a microphone or a speaker, but in this application it is only used as a speaker.
If you were turning an ordinary pen into a covert TRANSMITER then, yes.
I recall discovering this when I was playing with my dads 6 ft amplifier and a pair of amp headphones as a kid. Plug headphones into input jack and voila, microphone.
I find it amusing that as humans we can understand something with 100% clarity and still bitch as though it does not compute because of semantics. “Whats that you said speaker? Now there is no way I can understand or appreciate this, too bad it didn’t say mic..”
It’s not that nobody can understand it, it’s just wrong. It’s the sort of precise mindset that finds this annoying, that makes people good with technical stuff. Literal rule following.
In the case of language you can cut someone some slack, but calling a speaker a mic is stuff someone writing on electronics should know better than, it’s hardly like getting some complicated circuit’s name wrong. Wrongness really annoys some people. I’d say it was OCD but it’s nothing like OCD, that’s another popular misconception.
Well I feel silly. Somehow I had the word microphone in my head consistently through this article. I definitely intended to write “speaker”, but my fingers kept typing microphone. Weird.
Apparently feeling silly about a weird error is not enough to get the editors to fix the text in the article. This is another example of quantity over quality, we are not talking spelling, grammarnazi, or the fine points of semantics, a speaker is the only applicable transducer to use in a receiver and HaD readers deserve better editorial oversight or they will start seeking content elsewhere.
I dunno where else they’d go. HAD does pretty well, you should see some of the “techy” websites out there.
That said, most journalistic outlets employ sub-editors especially to correct things like this. It’s surely justifiable in a budget, when things like this happen all the time. Get a sub, HAD!
If I hook up a bone conduction microphone to a radio transmitter, will other people be able to hear the voices in my head?
Not if you are wearing your aluminium foil hat!
Brilliant
Well technically yes. If you mean your own voice. Though that’s also partly in your neck, so I suppose I’ve pedanted myself into a standstill.
cool i wonder if they slipped one in on me while i was KO’ed during wisdom teeth extraction hey you guys ever feel like your getting a x-ray hologram made of you for whatever reason you would be volunteered for such things? and so the tens device for muscle stimulation could something like this be used to increase reaction speed and timing in a individual making them extra survivable and enhanced covertly if it was implanted in the body? and what about something like implantable medical devices to keep a donors body fuctioning even after traumatic damage and dismemberment? and is there anything like a over the shoulder targeting system for use with targeting algorithms and weapons systems?
One app that would be also not so above the board, but maybe be able to listen to music while at work. Stick your pen in your mouth while you are at your desk and catch some tunes or sports cast. Or more above the board, anywhere you need your ears to be available to hear what is going on in your surroundings but you need to listen to something important. Hunters could use it out in the field where they need to listen but it gets boring when nothing is around so you can listen to weather broadcasts or news while out in the field and not have your ears totally incapable of hearing game walking through the forest.
If it’s possible for such a device to be of much help on an exam, then the exam is not designed very well.
+10000
Especially as you get to higher levels of education, the only people that you know that can help you on your “advanced microelectronic fabrication” exam (or whatever your flavor is), are probably sitting right next to you worrying about their own grade, not yours.
That is why you and your buddies have to take courses at different section/quarter/semester so you can help each other out! =)
basically, you could have an audio version of a ‘cheat sheet’ that looped. still, i mostly agree. i never found ‘cheat sheets’ helpful.
You can make teeny, godawful, FM radio transmitters that would fit into a pen. So you’d have two-way comms with a friend with Internet access and some textbooks. Maybe a throat mic would be good. Hide it behind a tie.
or just get one of these http://blogs.discovermagazine.com/discoblog/2010/02/02/my-other-ear-is-a-tooth-bone-conduction-helps-the-hard-of-hearing/
too bad they went bankrupt 1 month before you posted the link
Whenever I cheat on tests I prefer this stealthy method. You are guaranteed to not fail (d’oh!!!)
https://www.youtube.com/watch?v=gk5R9GmIsAs
To all you humorless sorts NOT in America… It’s a frickin’ joke OK??? :-)
I think specialhitech made these thing