It’s a phenomenon that has long fascinated the scientific community: When in a noisy, crowded room, a person will still prick up their ears if their name is mentioned. Equally, two guests can isolate what the other says from the surrounding cacophony. They are able to engage in a private conversation without speaking louder than those around them. This is known as the “cocktail party effect,” but it was air traffic controllers, not socialites, who led to its study in the 1950s after they reported finding it very difficult to listen to multiple pilots speaking at the same time through a single loudspeaker. British engineer Colin Cherry set out to understand which factors made selective hearing possible.

“It is an extraordinarily complex feat that allows the brain to ‘de-mix’ ...