In messages the couple have shared with the BBC, the anonymous Fiverr user says the audio will be used for research into "speech synthesis".

Recent advances in generative artificial intelligence have spurred developments in realistic speech synthesis.

In response to this evolving threat, Ning Zhang, an assistant professor of computer science and engineering at the McKelvey School of Engineering at Washington University in St. Louis, developed a tool called AntiFake, a novel defense mechanism designed to thwart unauthorized speech synthesis before it happens.

Deepfakes have become too good and too easy to make; just this month, Microsoft announced a new speech synthesis tool called VALL-E that, researchers claim, can imitate any voice based on just three seconds of recorded audio.

This is pushing entire sectors of information technology to new levels, including speech synthesis, systems that produce utterances that humans can understand.