There does not seem to be any limit to what the technology can do. Technology that could see an end to the bane of many commuters - people talking loudly on their mobile phones - has been shown off by researchers. The prototype device could allow people to conduct silent phone conversations.

The technology measures the tiny electrical signals produced by muscles used when someone speaks.

The device can record these pulses even when a person does not audibly utter any words and use them to generate synthesised speech in another handset.

“I was taking the train and the person sitting next to me was constantly chatting and I thought ‘I need to change this’,” Professor Tanja Shultz of the Karlsruhe Institute of Technology told BBC News.

“We call it silent communication.”