Rather than sound being pumped out from a loudspeaker in all directions, the Klang speaker concept proposes using a low level ultrasound to direct the audio only where it's required, leaving silence everywhere else. Such a system might allow audio output from a television to be sent to a different place in a room to sound from a hi-fi, allowing each listener to enjoy the experience without inconveniencing the other.

Industrial designer Adam Moller told Gizmag that while researching audio equipment for a six week speaker system project, he stumbled upon an online video featuring inventor Woody Norris. The successful tinkerer was demonstrating his Hypersonic speakers – a system that beams ultrasound at frequencies above the range of human hearing in a narrow column. This approach means that instead of being created at the speaker cone, sound is generated at billions of points along the path of the ultrasound beam where the high-frequency waves mix with "corruptions" in the air and are broken down to an audible range. The result: only those in the path of the beam can hear the sound.

Norris' directional systems are already used by the military as a type of "sound canon" but it's the potential consumer audio applications – where sound can be generated right next to the listeners ear – which grabbed Moller's attention.

"I was immediately inspired," said Moller. "I saw technology that had the potential to connect people to their audio like never before. I also saw an opportunity to take it one step further by making the signal spread adjustable. By having the signal originate at a single node and directing it into a dish, the node's relative position to the focal point of the dish determines the spread of the sound. This means you can focus the sound on just yourself, or spread the signal to fill a wider area if you have company. Now you can have the privacy of traditional headphones without the wires, discomfort, and isolation."

Such a system would also allow those looking for true binaural sound to point one transmitter at the left ear and the other at the right and enjoy faithful audio reproduction and without worrying about disturbing those around them. Sound absorbing objects within a room that can make or break great audio reproduction are almost completely taken out of the picture.

The Klang Ultrasonic Speakers are, sadly, just a concept model at the moment – created using a 3D printer with lathe-turned brass and instacast pieces. Moller says that the "underlying goals of this project were to get people to rethink what personal audio means to them, and to show where sound technology could be in the future."

With the ability to direct and control audio already being available thanks to Norris, that future may not be too far off.

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