Targeted Sound Beams

Mr_Kcleen writes: "Wired has a story on using sound beams targeted to only one person. They discuss various uses, from musical performances to possible weaponization." This is another one of those ideas that are right around the corner, really, honest.

Comments

60 kHz?

[tlotoxl]

Is all the energy converted to the audible range or do we get weird things going on elsewhere in the spectrum? Will dogs bark and birds flee?

Sounds like fun technology. I remember reading about it a while back, but had no idea it was being implemented in commercial projects. Portable mp3 players/discman seems like a better car solution to me, but some of the other applications are intriguing. Time to get myself to Tokyo.

Not as new as you might think

[fireboy1919]

Parabolic microphones and speakers have been around (commericially, even) forever. They already pretty much do this - picking up sound in a straight line from the source from a long distance away.

I guess this might work over a longer distance than parabolic stuff, but they haven't really shown that. So basically, they have a technology that can be duplicated by taking a regular speaker as the focus surrounded by a plastic parabola.

I wonder why they didn't bring that up in the article? Surely they've heard of it?

Beat Frequency

[jafuser]

This is actually a very simple concept, called beat frequency. I guess nobody ever thought to try it on ultrasonic frequencies to recreate frequencies that are within our hearing range. You may remember beat frequency from your high school physics class, if your teacher ever demonstrated the "weird effect" you hear when you strike two very slightly different tuning forks, you'll hear both tuning forks, plus a beat frequency that is equal to the frequency difference of the two tuning forks. You also hear the effects of beat frequency if two people try to make the same tone with their voice (such as when singing duet), it almost sounds like there's a third voice in there.

I saw a demonstration of this technology a few years ago at Epcot center, during the Discover Magazine Awards for Technological Innovation. The demonstrator held this paddle-like device with an array of metallic discs on it, and as he turned it slowly across the crowd, you'd not hear a thing until it was pointed at you. Very cool :)

Interesting, but not for concerts

[hcdejong]

From the article: Pompei imagined that instead of loudspeakers blaring the same cacophony of instruments to all parts of the room, it would be more interesting to selectively spotlight the soloist to the left side of the audience, while featuring the percussion up front, and then switching them around.

But when I go to a concert, I want to hear all the instruments - without having to move around the room.

Also, I get the impression that current tests are being carried out in silent environments with few obstacles. In a concert, you'd have to crank up the volume of such a 'sound spotlight' in order to hear it over the 'general' sound system. And in a crowded hall, the sound from the beam would be reflected more. This would cause the sound generated by the spotlight to 'leak' out of the beam area, making it less effective.

And (also important in a concert) the audio engineer can't hear what he's doing with the spotlights, making it very hard to get right.

Different technology

[maaaaanis]

The guys you're talking about are using a process which is all done within our hearing spectrum.
The use slight delays to fool our ears into thinking that the sound is surrounding us. The pinnea (ear flaps) are used to channel and delay sound as it enters our ear to give us an impression of where the sound is coming from, so as sound hits our pinnea from one direction, it gets to the eardrum at a slighly different phase than from other directions, our brain learns to interpret these differences and give a direction to the source.
The synthetic version of the process was called transaural. It was written up in the AES journals at least 7 years ago...

Whisperers arch

[Anonymous Coward]

Has anyone seen one of those at a museum? You stand beneath a parabolic arch and there are 2 focal points. If someone is standing in each of the focal points they can whisper to each other without anyone else being able to hear.

Also, if you go to the ruins of Chichenitza in Yucatan Mexico, you can stand in front of the pyramid and clap your hands and it comes back with a ricochet sound, but people beyond a certain angle can't hear anything but a clap..

Car navigation systems, laser pointers

[kuhneng]

I played with this at Bose a few years ago, and it's very disorienting at first. Pompei may have taken this further than the prototype I saw, but the version I played with essentially created audible sound coming from the point where the ultrasound beam reflected off of a surface.

It's very odd to play with one of these things. We put on a CD and started waving the ultrasound array (housed in a flashlight body) around the room. I felt disoriented pretty quickly as my brain tried to figure out where the sound it coming from.

One of the more interesting effects, as mentioned in the article, is pointing the array at someone's head and turning the volume down. Only the target can hear, because it's essentially like having a headphone on. The sound it's generating is simply too quiet to hear unless you're less than a few centimeters from the source.

My favorite application for this is car navigation systems. I like the idea of a GPS navigation system that can give spoken directions to the driver without bothering all of the passengers in the car.

Just imagine- some day these things could be as common and annoying as laser pointers. Imagine walking down the street with some teenager 200m away whispering in your ear. It's going to be ugly.

Conspiracy theory alert...

[cr0sh]

Want to learn something interesting? Look up "voice to skull" technology. I have managed to find direct evidence (via government websites) of both the United States and Austrailia researching this technology. Patents exist, and can be looked up. The technology is real, as has been known about for a few decades.

It looks like the tin-foil hat kooks may be right.

Two systems exist:

1. Audio over ultrasonic carrier - essentially uses the skull to filter the ultrasonic carrier wave - at that point it is simple bone conduction.
2. Audio over microwave carrier - this one is more "advanced" - it uses frequencies in the microwave region as the carrier wave for the sound. These waves then stimulate the vestibular region of the brain, which filter out the carrier and leave the sound information behind for the brain directly to figure out - causes strangeness to the recipient - a "voice in the head" type sensation. This form of V2S was first noticed by microwave and radar engineers who would "sense" or "hear" (in their heads) "clicks", "pops" and "whine" type noises as the worked around unsheilded microwave equipment.

Both of these technologies are real, as far as I can figure. Neither is "high quality" - but voice quality only (in fact, the microwave V2S system is actually pretty poor quality - rendering the voices in a "growling" type tone - which could be interpreted as "demons talking"). Both have potential "sinister" applications - neither have the quality of use for anything else.

I wish I was making this up - I haven't found anything that says "impossible" yet - but if someone could look into this with me, and let me know that I am wrong, I would love to see the information...