Voices in Your Head

ceejayoz writes "MSNBC/Newsweek is running a story about a 'Hypersonic Sound System' that can 'can take an audio signal from virtually any source and convert it to an ultrasonic frequency that can be directed like a beam of light toward a target up to 100 yards away.' Sounds like something that advertisers will love - Minority Report just got a little closer." These guys (and the Audio Spotlight guys) have been hyping this technology for years with nothing much to show from it. But now, Newsweek promises, it's going to change the world as we hear it.

Comments

Sonic Guns?

[cheesethegreat]

The technology creats a sound wave at the point where the two ultrasonics intersect. So, if the energy of the ultrasonics were high enough, or enough ultrasonic waves intersected close to each other, this could create a huge sonic force, enough to throw someone through the air, or knock down walls. Interesting weaponry applications, eh?

Re:Sonic Guns?

[dreamchaser]

Theoretically possible. Virbrations are a manifestation of kinetic energy, with air (in this case) being the medium. Given enough energy and the right harmonics, it could potentially at least knock someone over. Ever see a glass shattered by the right sound at the right intensity?

A more 'practical' weapons application would be as a type of stun device, though. Hell, they are getting ready to start deploying a sonic based 'non-lethal' weapon, it's already mounted on a destroyer. Supposedly makes it impossible to do anything but clap your hands on your head and cry 'make it stop' over and over.

Re:Sonic Guns?

[Jerf]

People's bodies do not have strong resonance frequencies. Without that, nobody's going to be "knocked over" by a sound wave.

"Stun" devices remain science fiction. In fact the idea that a person's nervous system could be somehow incapacitated with sound dates at least back to the late fifties, and you might be able to push it back to the forties or further with some research. (I know I've read fifties-era sci-fi that has sonic stun guns, though, so I'll stick with that.) In fact, it stems from the same misunderstanding promulgated by Star Trek, that everything has a resonance frequency and is just waiting to have havoc done to it by a passing vibrating object. It should not surprise you that the idea has fared about as well as the contemporary rocket jet packs and meals in pill form have fared in real life... what faint vestiges of them exist hardly resemble the '50's conception of them.

This page has a pretty good analysis on the topic, and should probably be considered required reading for all of the budding psuedo-science stun gun designers on Slashdot today.

(By contrast, simply blasting soldiers or rioters with high-energy sounds, distracting sounds, or even (perhaps ideally in the military sense) misleading sound is quite practical, even if less sexy.)

This is how it works in layman's terms

[wackybrit]

For some reason I feel this is a double post, but no-one here seems to have noticed, so I must be nuts.

Here's how it works in laymans terms. I am no science wizard, but this sounds good to me..

There are things called beat frequencies that occur when you have two frequencies present. For example, if you play 20Hz into one ear, and 25Hz into the other, your brain can be 'tricked' into thinking it is hearing 5Hz (the difference between the two frequencies).

This is all well and good, but 20Hz soundwaves don't travel too good. Ultrasonic frequencies do though. Remember those TV remote controls in the 70s and 80s that used ultrasonics? You could control your neighbor's TV. (See the start of Poltergeist 1 if you forget)

But how does sending 50Khz sound waves through the air help you hear anything? Ay, well there's the rub. The concept of beat frequencies is used once again.

If you send a 50Khz sound wave from one source and pinpoint it at a certain spot, and then send a 51Khz sound wave from another source to the same spot, anyone at the place where those two beams join up will hear a 1Khz sound, thanks to beat frequencies.

That's how you can pinpoint sounds to a single place. It just took a genius to get the connection between beat frequencies and ultrasonics to work this one out. I think it's cool.

Close, but no cigar

[wowbagger]

You got a few things right, but a few things wrong.

First, beat frequencies are quite real - there is no "tricking" your brain into hearing something that isn't there - the signal is there.

Specifically, whenever you feed 2 signals f1 and f2 into a system with any non-linearities, you will get four frequencies out - the original f1 and f2, and two new frequencies (f2-f1) and (f1+f2). So, if I feed 51kHz and 50 kHz into a system, you will get 1 kHz, 50 kHz, 51 kHz, and 101 kHz. This is the same principle that all modern radio receivers work on - it is called heterodyning, and a modern radio is a superheterodyne receiver.

Now, in terms of propagation, low frequency sound does better than high frequencies - hence why thunder goes "CRACK" when it is close and "rummmblee" when it is far away - all the high frequencies have been attenuated by the air. Also, this is one of the reasons why all you hear of the assholes with the ThunderThump 3000 car stereos is the low frequencies - what little high frequencies they produce are attenuated by the car's body and the distance.

However, to get any directionality from a sound transducer, it must be large with respect to the sound frequency. The problem is that the bulk of the frequencies humans hear have very long wavelengths - it is possible to make a directional beam of 20 Hz sound, but you would need a speaker system the size of a football field. Somewhat impractical if you want them all over the place, pumping out your "BUY ME NOW" message.

However, by translating the frequencies up to 50 kHz, you reduce the wavelengths down to the point where the speaker needn't be much larger than a paperback to get the directional gain you want. So, you upconvert the signals to ultrasonic frequencies, and you use the fact that just hitting a surface acts as a nonlinear mixing element.

However, I have always wondered how much of the signal is going into the (f2-f1) component, and how much of the power is in the other three frequencies you cannot hear? What kind of damage will this energy do over the long run?

Not to mention that, with the steady erosion of the respect of the right of people to be left alone, how will this be abused? Will we see "reality TV" shows freaking people out? (say, by beaming "LOOK OUT! HE'S GOT A GUN" to one person in a crowd). Let alone the targeted advertisments ("Hey lard butt! Yeah, YOU. Get your fat ass into Fred's Gym, across the street. NOW!")

Personally, if this sort of thing gets deployed in public places, I want to start carrying one of the boxes you used to downmix bat echolocation down to audible, locate the speakers, and use my Leatherman on them... Or my Browning...

What the hell is the buy lnux department?

[Anonymous Coward]

C'mon Please please refrain from hawking LNUX shares. Remember, as stated on Forbes.com ' VA is not a Linux company '.

Reminds me of...

[OneFix]

That scene in Real Genius...You know... ...
Mitch: And from now on, stop playing with yourself!
Kent: It is God! ...

Re:Newsweek Objectivity

[guttentag]

I was working for washingtonpost.com (officially called "Washingtonpost.Newsweek Interactive" because the organization was responsible for both publications' sites) when The Post announced its alliance with MSNBC.

One of the provisions of the alliance was that Microsoft would publish Newsweek.com. The first reaction I heard from my coworkers was a concern for Newsweek's objectivity, or at least the appearance of objectivity. The Post's top brass assured everyone that the deal would have no impact on Newsweek's objectivity. I'm not saying it has; just putting a little insider kerosene on your fire.

One of the other provisions was that washingtonpost.com would feature Windows Media clips of Washington Post reporters on MSNBC. We were instructed to embed the video in our templates and also call a .js file hosted on MSNBC's site. The sole purpose of the .js file was to weed out non-Windows browsers. For instance, I visited the page (on our site) with a Mac and was redirected to an MSNBC page stating "Windows Media Player is not available for the Macintosh." I showed this to one of the top editors, who replied our users should know better than to buy a substandard computer. I then downloaded Windows Media Player for Mac from Microsoft and demonstrated that the video works perfectly if you take the .js reference out. The next morning the multimedia editor was waiting at my desk to get the details, and later began re-encoding the video files in Real format -- over Microsoft's loud objections.

Bottom line: Microsoft tried to use its deal with The Washington Post to prevent non-Windows users from viewing Post reporters on The Post's own site. I can only imagine what goes on at "newsweek.msnbc.com."

Re:I'm inclined to think this is bullcrap.

[cybermace5]

Ok...I'm inclined to think you were born yesterday.

Ever been to even the most basic children's museum? Then you've seen the two parabolic reflectors that transmit a whisper clearly across a crowded, noisy room.

Ever cupped your hands around your mouth to shout to someone far away? You must have looked pretty stupid, if, as everyone knows, you can't focus sound.

Ever seen an amphitheatre? They're designed specifically to focus sound to the listening audience.

Those great big flaps of flesh that stick out of your head, that just happen to be rougly cone-shaped and connected to your auditory canal? What do you think those are there for? For that matter, ever seen a horse, dog, or cat when it's listening to something?

Sound is a wave, and can be focused. Everything exhibits both wave and particle properties, light can be focused because of its wave properties, not its particle properties.

You obviously skipped 1st grade physics.

Re:Newsweek Objectivity

[PRickard]

guttentag typed: Bottom line: Microsoft tried to use its deal with The Washington Post to prevent non-Windows users from viewing Post reporters on The Post's own site. I can only imagine what goes on at "newsweek.msnbc.com."

Excellent information, I appreciate the insider's perspective on that deal.

I've been opposed to the MSNBC agreement from day one for obvious reasons. I usually disagree with Ralph Nader, but he gave a pefect quote about Microsoft in 1995 or 1996...

"When you move from conduit to content, as Microsoft is doing--into publishing, into cable, encyclopedias, etc. you get another abuse of concentrated power. We've always believed the conduit should be separate from content."

I agree with this 100% and honestly think it should be made into law. Dangerous ground.

Back in 1995 or 1996 Microsoft came within a few million dollars of buying Turner Broadcasting (CNN, TBS, TNT, et al.). The Turner agreement was that Microsoft would basically purchase them for something in the area of $12 billion, then Microsoft's Turner subsidiary would use that money to buy bankrupt CBS. Imagine what kind of Microsoft we'd be dealing with if that agreement hadn't collapsed. Scary to even consider.

Non-lethal weapons

[Noofus]

There are some riot control devices that look like a cannon. They essentially consist of a massive multi-kilowatt power amplifier that is used to fire 10hz tones (lower limit of human hearing is around 20hz) at the crowds. "Loud" enough sound at 10 hz is enough to knock people over and make them lose control of their bowels.

I imagine this could easily be used to 'beam' a low tone like this at someone specific (a hostage taker, etc) and make them incapacitated without any harm to others in the area.

Check out Audio Spotlight

[emin]

As the headline of the story says, check out Audio Spotlight from MIT. I was lucky enough to see Joseph Pompei (the inventor of Audio Spotlight) give a demonstration and it was amazing. The technology works as promised: it produces a directed beam of sound which can make noises come from anywhere in the room you want. Furthermore, Mr. Pompei struck me as an exceptionally competent researcher. He had looked at a lot of issues like what kind of frequency response you can get (bass is harder to get than treble), whether the ultrasound causes long term damage (not according to a Harvard study), and how to manufacture (short answer: lots of DSP chips).

I don't new about the guy Newsweek talks about, but the technology is real and I'm looking forward to hearing it.

The company website

[NickDngr]

For those who are interested in things such as white papers on the technology, go to American Technology Corp. website. I used to work there... the article does not do it justice.