Siri’s voice is probably one many of us are familiar with. Many iPhone users speak to Siri on a daily basis, but have you ever wondered where Siri’s voice comes from? While these days Apple uses fancy machine learning and computer speech to generate Siri’s tone and inflection, back in the virtual assistant’s early days, her voice was based on a real person. We almost never found out who that real person is, either, and if Apple had anything to say about it, we probably still wouldn’t know.

Indeed, even though the voice lines that would eventually be used for Siri were first recorded way back in 2005 – two years before the first iPhone even launched – it wasn’t until nearly a decade later that we met the person behind the voice: Susan Bennett. Bennett revealed her role as Siri’s voice actor in a 2013 interview with CNN, which you can see embedded below.

Bennett explains that the original gig took place in July 2005, when she spent four hours, five days a week for the entire month recording voiceovers for a speech recognition system made by a company called ScanSoft (which later merged with Nuance Communications). Eventually, that speech recognition system was used by SRI International in the development of Siri following decades of research into artificial intelligence. In 2007, SRI International spun off Siri into a standalone business, with Dag Kittlaus, Tom Gruber, and Adam Cheyer serving as co-founders of the new company.

Fast forward three years later, and Siri was acquired by Apple in a deal orchestrated by Steve Jobs, just two months after it launched as a standalone app on the iOS App Store. Siri made its debut as an integrated iPhone feature on the iPhone 4S and the voice assistant has been with us ever since, through plenty of ups and downs. However, it wasn’t until 2013 that Nuance Communications confirmed that its voice recognition technology was at the center of Siri, which finally allowed all of the puzzle pieces of this particular mystery to come together.

Siri, of course, did not have just one original voice actor. Susan Bennett is the one we’re familiar with here in the United States, but in the UK, Jon Briggs served as Siri’s original voice, while Karen Jacobsen was Australia’s first Siri. All three of them recorded the lines that would eventually be used for Siri in 2005, and judging from an interview the three of them did with The Guardian in 2015, it sounds like none of them knew that their voices were being used for Siri until after the feature launched on the iPhone 4S.

What’s particularly interesting about this is that Apple has never confirmed who the original voice actors for Siri are. Bennett, however, is confident that she’s the original Siri, and after her reveal in 2013, CNN reached out to an audio-forensics expert who determined with "100%" certainty that Bennett’s voice and Siri’s voice are the same. Apple, for its part, has remained quiet about the history of Siri’s voice, and according to Briggs was even "rather dismissive" when he reached out to the company to offer his help in promoting Siri.

It probably won’t surprise anyone to learn that Bennett is a professional voice actor, as are Briggs and Jacobsen. According to Bennett’s IMDB page, she’s had roles in several movies and TV series. She’s even credited in a couple of songs on the soundtrack for Aqua Teen Hunger Force Colon Movie Film for Theaters, believe it or not.

Meanwhile, her Wikipedia page credits her as the voice of the public address system in Delta Airlines Terminals around the world, so if you’ve ever flown Delta before, you’ve probably heard her voice. She’s also been featured in ads for brands like Coca-Cola, Ford, McDonald’s, Hot Pockets, and Macy’s, and was even the voice of EMMA in the video game Persona 5 Strikers. It seems that even jumping between media formats, she can’t get away from voicing robots.

These days, Bennett is no longer the voice of Siri in the US, nor are Briggs or Jacobsen the Siri voice in the UK and Australia. Apple has made a lot of tweaks to Siri throughout the years, and the only way to hear Bennett as the voice of Siri today would be to find an Apple device with an OS that predates iOS 7 – not necessarily an easy task.

While Apple still uses recordings of actual people as the basis for Siri (before running them through its neural text-to-speech engine, as TechCrunch explains), we’re guessing that the people it uses aren’t even aware they’re recording lines for Siri. If they are aware, they’re almost certainly bound by some kind of non-disclosure agreement that prevents them from identifying themselves as one of the voices of Siri, because as far as we can tell, Bennett, Briggs, and Jacobsen are the first and only Siri voice actors to come forward.