As an airliner approaches you from a long way off, the sound is first heard as rumble, and, as it get closer and then directly overhead, the sound becomes increasingly boomier.

Coordinate term: PSBGM

Like soften'd airs that blowing steal, / When meres begin to uncongeal, / The sweet church bells began to peal.

“I still had my corporate job, so we would talk on GChat all day while I was at work,” says Olisa. (She’s still based in New York; Garner Valentine has since relocated to Georgia. Both are in their 30s.) “To the outside world, I was working diligently, but I was really kiki-ing with my friend.”