Sound, only for you

New research offering bendable sound waves that can reach only one set of ears could be the next tech revolution

- REWATI KARAN

IF SCIENTIFIC RESEARCH and development do not end up boggling the mind, then what is it even doing? A new research on sound may 'bend' the rules (pun intended) of how sound is heard and transmitted, forever changing the way we listen through wired or Bluetooth earphones, for example. Researchers at The Pennsylvania State University and Lawrence Livermore National Laboratory, Livermore in the United States, have developed sound that can bend itself through space and travel only to the ear in a crowd. It could allow individuals to hear music or a podcast without the use of headphones or earbuds – and without annoying anyone around them. Picture holding a personal conversation in the midst of a crowded street or in a busy metro, with no one else able to hear a single word of it. It appears to be straight from a sci-fi movie scene but in reality, it is an achievement now underpinned by experimental findings.

Localised sound

The research, titled Audible enclaves crafted by nonlinear self-bending ultrasonic beams published in Proceedings of the National Academy of Sciences (PNAS) earlier this year, is based on the concept of 'audible enclaves' — strongly localised areas of sound created at precise points in space, invisible and silent to everyone beyond them. "Delivering audible content to a targeted listener without disturbing others is paramount in audio engineering. However, achieving this goal has long been challenging due to the diffraction of low-frequency (long-wavelength) audio waves in linear acoustics. Here, we introduce an approach for creating remote audio spots, dubbed audible enclaves, by harnessing the local nonlinear interaction of two self-bending ultrasonic beams with distinct spectra," wrote the researchers. In other words, they have developed a technology that could create sound exactly where it needs to be – to be heard by the recipient.