Ever since Apple first unveiled the iPhone 4S and its integrated digital assistant Siri, I’ve become more and more accustomed to seeing people talk to their smartphones. But a thought occurred to me the other day; how does Siri talk back. Does Apple have a prerecorded set of things Siri can say, or is it more complicated than that? Has Siri been taught how to speak?

The Verge has a fantastic feature on how companies like Nuance have found a way to translate a human voice into a machine’s voice. If you get a few minutes it’s definitely worth a read but at the very least watching the video below will do the trick.