A new speaker system based on ultrasound is able to direct sound in a narrow beam to an individual, allowing them to hear audio without disturbing those around them.
Researchers at South Korea’s Pohang University of Science and Technology (POSTECH) developed the speaker, called MiPAL, that is able to deliver sound within a targeted area.
One of the bugbears of public transport is the noise of other passengers, including music from commuters or frequent announcements. While conventional speakers emit audible sound that naturally spreads in all directions, a newer technology called parametric array loudspeakers (PAL) instead emits high-frequency ultrasonic waves that travel in a highly focused, laser-like beam. However, the system requires the precise arrangement of tens or hundreds of individual ultrasonic transducers, each of which needs to be individually controlled which makes traditional PALs complex and expensive.
To address this complexity, the research team integrated two types of...