Around 1990, German researcher Karlheinz Brandenburg sat in a lab listening to Suzanne Vega’s a cappella recording of Tom’s Diner thousands of times. He was tuning an algorithm built on a quirk of human hearing called auditory masking, first documented in 1894 by physicist Alfred M. Mayer: a loud tone makes a quieter neighboring tone inaudible. Brandenburg’s idea, finalized in his 1989 doctoral thesis, was that a computer need not store sounds the brain throws away.

This episode traces the MP3 from that biological insight to worldwide disruption. At the Fraunhofer Institute, Brandenburg and a team known as the original six turned the theory into working code, then watched a standards committee reject it as too demanding for early 1990s hardware. The compromise that followed became MPEG-1 Audio Layer 3. Fraunhofer planned to license it to broadcasters. A hacker, a leaked encoder, Winamp, and Napster had other plans.

• A lone voice exposes compression flaws that a dense symphony would hide, and Tom’s Diner produced a ghostly spatial artifact that took endless tweaking to remove. Brandenburg called Vega the mother of the MP3.
• The team’s codec, ASPEC, was merged with the simpler, hardware-friendly Musicam standard to win approval from the Moving Picture Experts Group.
• The .mp3 file extension was settled on July 14, 1995. Before that, the files used the extension .bit.
• A hacker in the Netherlands called SoloH found the reference encoder’s source code unprotected on a university FTP server and released it with a point-and-click interface.
• The format outlasted Sony’s ATRAC and Microsoft’s Windows Media Audio, and its last foundational U.S. patents expired in April 2017.