They created the bubble using an acoustic levitation device, a machine that can make small objects float in midair thanks to ultrasound. These devices can be used to keep small objects suspended ...

These bubbles are called active bubbles or acoustic bubbles ... research provides new insights into the relationship between bubble temperature and chemical activity," Professor Okitsu exclaimed.

A new invention has proven that audio can successfully be transmitted directly to a listener's ears without being audible to others around.