Directed Sound

yawningyellowyak writes "Technology Review has an interesting article on directed sound. Ultrasonic 'sound' is sent out from a 'speaker' and the distortion encountered on hitting the air produces hearable sound, but only in certain spots. You could be standing right next to someone and they would hear nothing. One step closer to the cone of silence!"

Comments

Cone of Silence? More like cone of annoyance.

[Maestro4k]

Seriously, marketers will be in heaven, able to target ads at passerbys. Now you can look forward to being inundated with directed sound ads while walking the street. It'll be far more annoying because it'll be harder to ignore than ambient noise (ads running on outside speakers, people hawking their businesses on the sidewalk).

And we think spam is bad...

Hope it will work for "boom cars"

[old man of the c]

But I doubt the car owners would want it. Why have a loud sound system in a car if the whole world can't hear (and know about) it.

The Lucas Sound Studio @ Disney

[adzoox]

Has anyone ever been into into the Lucas Sound Studio at MGM in Disney world? I believe it's co sponsored by AT&T.

* There's something similar to this. You put on headphones.

* You're in a booth about the size of a small 1/2 bathroom.

*It goes completely dark, but you are told to close your eyes for an even better effect.

You then proceed to "become a CEO" for a day of a Fortune 500 company - you get your hair cut and blowdried in the boardroom - you CAN FEEL the scissors and hear them close to your ears and atop your head. Then you can FEEL HEAT from the blowdryer - and it's nothing but sound rather an auditory/perceptual illusion.

Imagine if this could be done with the directory sound.

Re:The Lucas Sound Studio @ Disney

[Shawn Parr]

This is actually accomplished through Binaural recording. It is achieved by created a human shaped and sounding head and putting microphones where the ears are. It works by accurately capturing the phase relationships in addition to the normal frequency and volume differences heard between your ears. Quite different technology as in order for it to work you would have to have exquisite aim with not just one beam of sound, but two, one for each ear.

Already in use

[Big Nothing]

This kind of technology (although not as refined as mentioned in the article) has been in use for quite some time. For example, in Oslo Lufthavn (Oslo/Norway international airport) there are "quiet spots" where a speaker is used in combination with a parabole to create "sound spots" in the airport lounge area. The sound (sea waves, bird song, etc.) is basically only audible to the person standing directly under the speaker/parabole.

Frequency change=nonlinearity=high levels

[dpbsmith]

Linear transformations cannot create new frequencies, only alter the relative intensity of frequencies that already exist. If ultrasonic sound is being heard, some nonlinearity somewhere is converting it to audible sound.

The thing that I have to wonder about is that this kind of nonlinearity implies fairly high (ultrasonic) sound intensities, and suggests that stuff inside your head is being driven beyond its elastic limit. The big thing that seems to me to be missing from the article is any statement of the ultrasonic sound power level, in decibels, that is being delivered to your head (and the ratio between the actual ultrasonic sound level and the apparent audible sound level).

How does this compare, for example, to the sound levels used for ultrasonic imaging in medicine?

I'm not suggesting that the process is necessarily dangerous, but it isn't obvious that it's intrinsically safe, either. It's one thing to be subjected to high-power ultrasound a few dozen times during your lifetime for the purpose of preserving your health. It's quite another to be subjected to it day in and day out, for your convenience in listening to music, or for some advertiser's convenience in interrupting your train of thought.

Re:Can I smell something ?

[hal200]

FWIW, I saw this demonstrated on The Screensavers on TechTV a couple months ago. It seemed to work when they turned it on the studio audience. Only the people that the machine was pointed directly at could hear it. It could have been an elaborate hoax, but then again, so could the Moon Landing...

neither one

[ashot]

will dominate this market, because there is a new technique in acoustics that will eclipse the ultrasound method. Using something called time reversal, you can pinpoint the output of sound to a single location in 3 dimensional space, focusing around objects, people whatever; no beam, no drop off.

This focusing can be done with more than just sound waves however, and the first applications are in medicine, however, it does apply to sound as well.

The basic idea is that if you create a sound from some source location, and record all of the noise at another location, then play this noise signal backwards from the recorded location the sound will reappear in the one spot from which it was originally played. An analogy is that if you take a pool ball, put it right in front of a pocket, and then bounce it outwards really hard, letting it bounce against the walls multiple times, but noting the exact location of the last bounce of the ball, then if you reshot the ball at the exact spot where you last saw it bounce, it would go back in the whole.

HyperSonic Sound (HSS)

[andrewHYC]

The company producing the equipment is American Technology Corporation at http://www.atcsd.com/tl_hss.html According to their own site one test showed a level of 110 db at 2 metres at 48KHz giving an apparent audio level (3 KHz) of 95 db. The level at 16 metres was 80 db at 48 KHz and still 90 db at 3KHz. Apparently they are already installing them in soft drink dispensing machines in Tokyo. (We soon won't know who is schizophrenic and who isn't). Cheers

These things can be dangerous

[Charles Dart]

My wife went to an tech award show last year at which this product won something. The presentor mentioned that the pentagon was also interested in the product. He said that it is possible to turn the volume up to lethal levels.

Re:Messin with people

[E10Reads]

Actually, this is already being implamented by the US Military in Iraq. It is used at checkpoints to speak to aproaching parties. And the Military has signed a new contract with American Technology for $1.1 million to deliver these LRAD's (long range acoustice divices) to the Marines. "LRAD is a breakthrough long-range hailing and warning, directed acoustic device that is designed to determine intent, change behavior, and support various rules of engagement. With LRAD, a sentry can issue a focused verbal challenge with instructions in excess of 300 hundred yards, and follow up with a warning tone to cause behavior change. Recorded messages can be selected and delivered over LRAD in multiple languages."[from an American Technology press release. regarding this contract] So far this is the biggest contract the company has and most likely, for years to come, the most lucrative applications will come from military applications, both as defense and as weapons. But ultimatly, comercial application will exceed the military in the technology's application and source of revenue for ATC.