Special transverse sound wave

Research team at City University of Hong Kong (CityU) has discovered a new type of sound wave: The airborne sound wave vibrates transversely and carries both spin and orbital angular momentum like light does. The findings shattered scientists’ previous beliefs about the sound wave.

“While the airborne sound is a longitudinal wave in usual cases, we demonstrated for the first time that it can be a transverse wave under certain conditions.”

Researchers designed a type of artificial material called “micropolar metamaterial” to implement this idea, which appears like a complex network of resonators. Air behaves like an elastic material inside the micropolar metamaterial.

The findings demonstrated that airborne sound, or sound in fluids, can be a transverse wave and carry full vector properties such as spin angular momentum the same as light does. This may have applications in acoustic communications, acoustic sensing and imaging.

Read more at
https://www.cityu.edu.hk/research/stories/2021/12/09/cityu-physicists-discovered-special-transverse-sound-wave
https://phys.org/news/2021-12-physicists-special-transverse.html
https://www.eurekalert.org/news-releases/937147
https://www.nature.com/articles/s41467-021-26375-9
https://www.physicsclassroom.com/class/waves/Lesson-1/Categories-of-Waves
https://www.pasco.com/resources/blog/237