Research: Method found for transmitting audio signals without headphones

Researchers at Pennsylvania State University have found a method of transmitting audio signals using two non-linear ultrasonic waves. This makes it possible for a person to perceive the audio signals at a certain point, but no one else around them. The discovery could make it possible in the future to listen to music or podcasts without having to wear headphones and without anyone else hearing it, the university says.

“We use two ultrasound transducers paired with an acoustic metasurface that emit self-curving beams that intersect at a specific point. The person standing at this point can hear the sound, while other people standing nearby cannot hear it. This creates a barrier between people that enables private hearing,” co-author Yun Jing is quoted as saying.

Two inaudible frequencies

The two frequencies emitted by the surface are slightly different and cannot be heard individually. Only when they meet at a certain point makes the sound become perceptible to humans. This creates what the researchers call an “acoustic capsule”. In addition, the individual signals can avoid obstacles such as other human heads to reach their target point.

The application was tested in rooms with other people and normal reverberation, which also makes outdoor or classroom use conceivable, according to the university. Head of research Jia-Xin Zhong describes the new development as a kind of virtual headset.

Currently, the signal can be transmitted over a distance of one meter at 60 decibels. The researchers hope to increase both values by amplifying the intensity of the ultrasound.

(tlz)