I've told a lot of people about this, but forgot to blog about it. Shame on me, because this revolutionary concept can change the way we think of sound.
Audio Spotlight enters the category of directional sound systems, more precisely it creates sound from ultrasound. The result is that you can direct a single speaker towards a certain area, and only people in the area can hear the sound.
There are drawbacks, as obstacles getting in the way of the sound beam block the sound from reaching further on. There are limitations to the frequency response and the dispersion pattern. I also don't know if the system can create loud sounds as this would probably need high power ultrasound and I don't know how healthy that would be.
But, even so, the idea is marvelous. As you can see from the animation from the Audio Spotlight site, you can attach a sound to a picture in a gallery, and the sound will only be heard by the people in from of the picture. Imagine that in a museum. Or think about having a restaurant with audio spotlight above the tables, playing whatever music they want and not bothering the other people. Combine it with some form of sound barrier between tables and you get a classy private place with no walls and a lot of people. Or think of a disco where you can separate the sound of each instrument and play it in a slightly offset area so people can dance to the music equalized however they like it. Or even a club where people can hear the music loud on the dance floor and really weak at tables, so they can talk.
This invention comes (of course) from MIT, more precisely from Dr. Joseph Pompei while he was a student at the MIT Media Lab, himself son of another distinguished doctor, Dr. Francesco Pompei.
However, with great power comes... ah, forget Spiderman! Anyway, there are voices expressing concern on the evil use of such technology. Like this link here, expressing the opinions of Barry Blesser, one of the most respected names in digital audio.
Now, I guess that the best invention ever would be directional earplugs! :)