Science News

Speech stopping ray

Sun, 4th Mar 2012

Dave Ansell

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If you have ever been annoyed by someone chatting in a meeting, or even in a concert, help migRCA 44 Ribbon Microphoneht be on its way.

Kazutaka Kurihara and collegues have built a device which can stop someone speaking from across a room. It takes advantage of an effect you may have noticed when talking on a very bad phone line - if there is a delay of about a quarter of a second between you saying something and hearing yourself it is almost impossible to talk, because your brain is listening to your speech as you are talking, and using that to control that speech. If you hear yourself slightly delayed the whole system gets confused and you start to stutter, and find it very difficult to talk at all.

So they have mounted a very directional microphone next to a very directional loudspeaker with a laser pointer for aiming. When they point the device at someone speaking, it picks up the noise coming from that direction, and then plays the sound back at them with a delay adjusted for the time sound takes to travel that distance, causing the speaker to stutter and have great difficulty talking.

They are not intending to manufacture these devices but the technology is very simple so it is inevitable that someone will, which brings up interesting ethical issues as it would be possible to point it at a lecturer for a laugh or more sinisterly use the device at a political meeting to silence a competitor.



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I'm sure you can circumvent it by earplugs and a throat-mike, sending what you say directly back into your ears?
Maybe one would have to experiment a little to find the right setting but it should work.
Or just earplugs may be enough? yor_on, Tue, 6th Mar 2012

Long ago when I was at school someone had built a digital delay line and we were playing with it. One trick was to give someone headphones and feed their own voice back to them delayed by a few tenths of a second.
It reduced most of us to stuttering  wrecks.
But not for long.
We learned to more or less ignore it. Some of us (like me- as it happens) learned very quickly.

A pair of noise cancelling headphones would immediately kill the effect for the benefit of those who didn't or couldn't learn to ignore the "interruptions".

Incidentally, IIRC, none of my musical friends learned to play a keyboard with the same set up. They were good enough musicians but it just flummoxed them.
Bored chemist, Tue, 6th Mar 2012

Here's a link to an interview with the creator of the device. This link was kindly tweeted to us by a follower:

Chris chris, Sat, 10th Mar 2012

One thing you have to say for the Israeli, they don't sleep much.
"* An Israeli consultant in Defense asked us very specific details of the effectiveness of the device."

But to make it really effective I think you need to imprint it in the skull bones, so they vibrate at some same pitch*? Frequency? wavelengths? Wasn't there tries with inducing nausea using similar devices, I have a vague memory of reading it somewhere, quite some time ago. Maybe you could 'steal their sound' too as electricity always is faster than sound, well, as far as I know, so far :)
yor_on, Sat, 10th Mar 2012

After speaking with Kazutaka about the device, I quickly realized how ineffective it really is under anything other than controlled and measured use. This device would be wholly noneffective if the subject were to make simple adjustments or be in certain environments. This device needs to be used under a strict controlled environment in order to be truly useful. It could not shut up a crowd. It could be used against a single person, but certainly not with any subterfuge or stealth necessary to make it a weapon against human rights. Dr. Kazutaka Kurihara made a neat device with the help of his colleague Dr. Koji Tsukada, to make use of a phenomenon of cognitive speech processing disturbance. I would call him brilliantly creative. Sadly, this device falls far short of this dystopian speech squashing smart-bomb that I have seen reported and commented on about this project. Either way, the debate is building interest in his project and getting him some recognition. Something I am all for! Stay Creative, It's Good For You. Grin, Sat, 10th Mar 2012

Yep, creativity is good.

Let's hope it gets used wisely though :) yor_on, Sun, 11th Mar 2012

Lets be clear about this.
For at least some speakers- of whom I am one, this simply doesn't work.
My recollection was that, to be simplistic, the self confident  assertive ones among us had the least difficulty overcoming this technique.
The people who stand up at political rallies and talk are already well trained in ignoring interruptions from the crowd.

I'm pleased to see that various "defence" groups are going to look into this. It means they won't be spending those resources on something that might work.

It reminds me of the story of NASA spending millions on a pen that would work in space- the Russians used a pencil. (and I don't care if the story is true).
The secret police spend millions on this- But it's defeated by a 0.20 pair of earplugs.
Bored chemist, Sun, 11th Mar 2012

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