A wearable device that could allow soldiers to whisper to each other without enemies hearing has been tested by researchers.

Project Telepathy, which is still in its prototype phase, uses ultrasound to beam someone’s words to another person. Some of the equipment used by the research team at the University of Bristol means the person you’re trying to communicate with could be 30 metres away and could still hear you.

The researchers say you don’t even have to make an actual sound for the device to work. Surface speakers are put on the head or chest of whoever is speaking, and four electrodes are attached to their face. Signals that their muscles generate when they silently mouth words can then be picked up, through a process called electromyography, and a machine learning algorithm is used to differentiate what word they are pronouncing.

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The next part involves ultrasonic speakers playing a recording of whatever has been mouthed and this is then blasted through the air. They are directional speakers, a bit like a laser, meaning that the sound only reaches its target, rather than spreading everywhere.



Dr Asier Marzo, co-author of the research, said that being on the receiving end of a message from the device is a strange experience.

He explained: “When you are blasted by an ultrasonic speaker it is not a very loud sound, so it’s like somebody is speaking very close to you but then nothing is there. So the receiver said it’s a weird experience.”

Soldiers from The Royal Tank Regiment walk through rows of Challenger II main Battle Tanks
(Ben Birchall/PA)


Talking about its potential to be used by soldiers, Marzo added: “If you have lots of soldiers in the field, and they need to communicate to each other, they wear helmets so the system could be integrated and they could communicate with each other over long distances and without the enemy intercepting the message.”

The technology could help divers communicate over long distances in the future, as ultrasound travels particularly well under water.

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But how successful was the testing? Well, through the use of a machine learning algorithm, the device was able to recognise the electrical muscle signals associated with 10 words, including “yes” and “no”.

(Asier Marzo)


And they discovered the system could recognise the correct word more than 80% of the time.

Marzo added that while Project Telepathy is just a prototype at the moment, and that the technology of recognising the words needs to be improved, the directional speakers are “amazing”. In fact, they are hoping to release a directional speaker that everyone can use within six months’ time.

He said: “We were thinking in the classroom, if you have a blind kid, or a kid that needs extra audio information, you can blast audio guidance only to that kid without disturbing the whole class.”

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