order music over phone lines. Given that audio file sizes were so large, the German patent office refused to approve something it deemed impossible. The professor asked a young graduate student named Karlheinz Brandenburg to work on compressing the files.7 Early compression schemes were available for speech but they were “one-size-fits-all” solutions, treating all files alike. Brandenburg developed an adaptive model that could respond flexibly to the sound source. That enabled him to craft his compression schemes to fit the particular nature of human hearing. Brandenburg knew that our brains hear selectively: for instance, loud sounds mask fainter ones, and low frequency sounds mask high ones. Using this knowledge, he could delete or reduce the unheard frequencies without a loss in quality. Brandenburg’s biggest challenge was a solo recording by Suzanne Vega of the song “Tom’s Diner”: a female voice singing alone and humming required hundreds of attempts to get the fidelity just right. After years of fine tuning, Brandenburg and his colleagues finally succeeded in finding the optimal balance between minimized file size and high fidelity. By giving the ear just what it needed to hear, audio storage space was reduced by as much as 90 percent.
At first, Brandenburg worried whether his formula had any practical value. But within a few years digital music was born, and squeezing as much music as you could onto your iPod became a must. Breaking acoustic data by flexibly throwing out unmissed frequencies, Brandenburg and his colleagues had invented the MP3 compression scheme which underpins most of the music on the net. A few years after it was coined, “MP3” passed “sex” as the most searched-for term on the internet.8
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