Penn State University scientists have unveiled a groundbreaking technology known as "audible enclaves," which enables private sound delivery to a single person in a crowd—without the need for headphones or any wearable device.

What Are Audible Enclaves?

Audible enclaves are localized pockets of sound that only a targeted listener can hear, while everyone else remains completely unaware. This technology uses intersecting ultrasonic waves to focus sound precisely at a chosen location. The audio becomes audible only at that intersection point—moving even slightly away means the sound vanishes.

How Does the Technology Work?

The Penn State engineering team, led by Professor Yun Jing and postdoctoral scholar Jia-Xin “Jay” Zhong, built their system using two special ultrasound transducers paired with 3D-printed acoustic metasurfaces—submillimeter structures that bend and steer sound waves on curved paths. The beams, which travel at slightly different frequencies, combine at the intersection point through a process called acoustic heterodyning, generating audible sound only at that exact spot.

• The system can bend sound around physical obstacles, such as heads or furniture, making it incredibly precise.

• Initial tests showed the system could deliver conversation-level sound (around 60 decibels) to a point about a meter away from the source in realistic environments.

• Simulated testing with dummy heads confirmed that only the target location heard audio, creating “privacy zones” even in crowded spaces.

Why Is This Important?

Traditional sound delivery methods—like loudspeakers or directional speakers—allow sound to be heard along an entire path, making privacy impossible. Audible enclaves confine audio to an invisible bubble, enabling private listening in public without disturbing others or requiring headphones.

• Applications could range from museum guides, private communications in offices, entertainment venues, automotive sound zones, or secure public messaging.

• This technology could fundamentally change how sound is experienced in shared environments, improving personal privacy and comfort.

Who Developed Audible Enclaves?

The invention is the result of collaborative research by the Penn State College of Engineering and Lawrence Livermore National Laboratory, with key contributions from Professors Yun Jing, Jia-Xin Zhong, and LLNL scientist Xiaoxing Xia.

^🌟 Support for this work came from the U.S. National Science Foundation and Lab Directed Research and Development programs.

What’s Next?

The technology is still in development, with researchers aiming to extend its range, increase volume, and explore real-world practical applications. Future uses could go beyond audio privacy—spanning encrypted communications, advanced spatial audio, or even medical imaging.

This Penn State breakthrough, published in March 2025, opens a new era for personalized sound delivery—one that is precise, private, and unobtrusive.