You won’t recognise her face, but you’ve certainly heard her voice.

The calming tones off Karen Jacobsen are used by more than a billion GPS devices, smartphones, elevators, cruise ships and software applications.

Most famously, she’s the Australian voice of Apple’s digital assistant, Siri, which she recorded the speech for over three weeks, with Karen unsure what the 50 hours of voice recordings she did were going to be used for.

“I’m told I’m part of pop culture history and there’s something pretty fun about that, I’m clear I have a lot of other ways to contribute to the world but it’s pretty exciting when people meet me and want to share stories about me, and the wonderful trips we’ve taken together… it really does uplift people and that’s very enjoyable,”  she told Liam Bartlett on 6PR Mornings.

Tap PLAY below to hear how Karen came to be Siri – and some of her famous voices