And since ultrasound travels in a tight line akin to laser light, the emergent tones are audible only in a narrow, cylindrical path from source to ear.

FORBES: Now Hear This

Five different boarding groups will line up in different areas, akin to how Southwest lines up customers by groups, so that instead of a crush of people pushing toward the gate, each group will have a designated place to wait.

WSJ: Summer Air-Travel Survival Guide