Last Friday’s Jones Seminar at Dartmouth revealed a new, radical technology that will “force people to rethink their relationship with sound,” according to an article in the New York Times. Invented at MIT by Holosonics founder Joseph Pompei, the Audio Spotlight allows extremely narrow beams of sound to be generated via the interaction of ultrasound waves in air, granting the ability to direct “sound like a laser” through virtually any environment.
Pompei began his presentation with a look at traditional loudspeakers. Needless to say, experience spoke volumes with regard to understanding. Sound from loudspeakers fills the room omni–directionally, thus providing no audio isolation and severely limiting the ability to have multiple sources of sound in the same space. Ultrasound, on the other hand, provides a different listening experience by sending narrow, concentrated beams of sound through the air. The air is then used to convert the ultrasound into audible sound as it travels. Physically, the Audio Spotlight uses a collimated beam, or collection of parallel waves, of ultrasound to send multiple waves through the air. This method creates difference tones that use the air to demodulate, or decode, the ultrasound into audible sound.
Pompei then discussed how he created a market for the Audio Spotlight. The beauty of the device, according to Pompei, is in its ability to direct sound not just to those who want to hear it, but also away from those who don’t, highlighting the importance of the Audio Spotlight’s message of “preserving the quiet.” Simply stated, the Audio Spotlight sells “surround silence” as opposed to surround sound.
This concept has led to applications in various fields. Advertising agencies have taken advantage of this technology, installing Audio Spotlight panels in supermarkets so customers hear about only the items that are directly in front of them without disturbing other customers. Billboard providers and airport security divisions have implemented the technology for similar, public announcement–type purposes. Hospitals and libraries have also installed the Audio Spotlight in order to allow some people to listen to media devices without distracting other patrons or employees. The technology has even been implemented by the military, which uses the directed sound waves to identify the locations of hidden land mines.
Pompei concluded the presentation with a demonstration of the device and a discussion of future consumer applications. After showing how the sound could only be heard when pointed at a specific section of the audience, or bounced off the walls accordingly, Pompei compared the device to a flashlight, reinforcing the analogy of this technology to sound with laser technology to light. He hopes to one day allow for large–scale implementation of Audio Spotlight, coupling this technology with other innovations that will allow people to share physical space without sharing acoustic space.