Chances are, when you think of Cher, the iconic recording artist, you also think of geophysics. Okay, maybe you don’t. But you should. Cher and geophysics revolutionized the recording industry – together.

It started in 1998, when Cher released her single “Believe.” The song was a major success, sitting at #1 on the Billboard charts for four straight weeks. It also featured a new, and peculiar, effect on Cher’s vocals: at key moments, her voice wobbled uncontrollably, like a robot attempting karaoke. The description sounds cringe-inducing, but combined with the song’s fast-paced beat, it sounds, well, good. Good enough to be adopted by Madonna, Janet Jackson – even rappers T. Pain and Kanye West. The “Cher effect” (as it became known) was soon a staple of the recording industry, a distortion process reinvented as an artistic choice.

So where does geophysics come in? Just ask Dr. Andy Hildebrand, an electrical engineer and the inventor of Auto-Tune, a pitch-correcting software and the source of the “Cher effect.” From 1976 to 1989, Hildebrand worked as a research scientist in the geophysical industry, mapping potential drill sites for oil companies like Exxon. He left the industry to pursue his first love, music. But his background in geophysics would come in handy in 1996, when a friend’s wife wished aloud for a device to correct her singing. “I knew how to do it instantly from my geophysical training,” he says.

The “how” of Auto-Tune is based on a mathematical formula known as autocorrelation. In geophysics, the formula can be used for seismic signal processing, the same process Hildebrand used to detect oil sites. “It was well-known from my early days in graduate school that autocorrelation had certain mathematical attributes that allowed for the detection of periodic signal,” says Hildebrand. Which made it perfect for processing seismic data, and, with some meddling, detecting pitch. “What I did was push the formula around a bit, and if you would, invent a new mathematics to use the attributes of autocorrelation to detect pitch.”

And Hildebrand’s work did more than basic detection; it made the pitch-changing precise, accurate, and without artifacts. With Auto-Tune, a so-so singer can become a pitch-perfect performer. It’s a neat trick, for sure, but Auto-Tune’s value goes beyond pleasant vocals. “The biggest change is studio time for singers is greatly reduced, reduced by half,” notes Hildebrand.

It’s an advantage that can’t be ignored. Multiple takes (the standard before Auto-Tune’s invention) cost the recording industry in time and money; and singers struggled with hitting the right notes while delivering an emotional performance. “With Auto-Tune, they just record [the song] once and the singer goes home,” says Hildebrand. Songs get polished vocals, full of emotion, and recording studios reduce costs. It’s a win-win situation.

And then there’s the strange case of the “Cher effect.” Auto-Tune works by nudging pitch to the nearest note on a scale. It’s a gradual change, barely noticeable to even a trained ear. But if you crank up the response time, the pitch changes instantaneously, and that’s the “Cher effect.” “We put that in the original software as a case that was kind of fun, but no one in their right mind would ever use,” explains Hildebrand.

Now, over a decade since its invention, Auto-Tune is a recording industry standard and its distortion effect seems to be growing in popularity. In 2009, the “I Am T-Pain” app hit the Apple’s iTunes store, allowing users to mimic rapper T-Pain’s heavy use of Auto-Tune with their own voice. In the same year, the Gregory Brothers, a Brooklyn-based musical group, started to apply the effect to popular news segments, which went viral on YouTube.

And while there’s been some backlash against the software – some artists maintain it’s a cheat for the untalented – it’s hard not to recognize its impact over a relatively short amount of time. A funny idea, considering the software was almost a throwaway idea. When his friend’s wife mentioned the idea for Auto-Tune, Hildebrand didn’t exactly have an “eureka!” moment. “I thought, ‘Well, that’s a lousy project. Nobody cares.’”

Though now Hildebrand is proud of his invention. “It’s a source of immense gratification to me…and it’s kind of nice to have invented a tool that’s so useful to so many people.”

But that’s what happens when science and entertainment sing a duet – innovation happens and impact follows. And now, whenever you tap your foot to a song sung in perfect tune, you know who to thank: a musical engineer named Hildebrand and an amazing science known as geophysics.

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