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.

国际信息及通信技术博览会上，研究人员向大家展示了一种装置，有了它，大家在上下班公交车上可能再也遇不到大声打电话的人。

kit¹ is still very much at the prototype stage" width="226" height="170" src="/upimg/100307/4_065212_1.jpg" />
The kit is still very much at the prototype stage

The prototype（原型，标准） 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（可听见地） utter（发出，表达） any words and use them to generate synthesised（人工合成） 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."

Translation system

The device, on show at the Cebit electronics fair in Germany, relies on a technique called electromyography（肌电描记术） which detects the electrical signals from muscles. It is commonly used to diagnose certain diseases, including those that involve nerve damage.

The prototype that is on display in Germany uses nine electrodes that are stuck to a user's face.

"These capture the electrical potentials that result from you moving your articulatory（关节的） muscles," explained Professor Shultz. "Those are the muscles that you need in order to produce speech."

The electrical pulses are then passed to a device which records and amplifies² them before transmitting the signal via Bluetooth to a laptop.

There, software translates the signals into text, which can then be spoken by a synthesiser（合成器） .

In the future, said Professor Shultz, the technology could be packed in a mobile phone for instantaneous（即时的，瞬间的） communication.

"We know this is not appealing for mass market use at the moment."

However, she added, it could be initially³ used to help people who have lost their voice due to illness or accident.

It could also form the basis of an instant translation system, she said.

"You could speak in your mother tongue and the text could be translated into another language," she said.

"The person that you are communicating with would then hear the synthesised voice in the other language."

It is not the first time that electromyography has been explored for silent communication.

The US space agency Nasa has investigated the technique for communicating in noisy environments such as the Space Station. It has also used the technique to explore advanced flight control systems that do away with joysticks（操纵杆） and other interfaces⁴（界面，接口） .

Nasa, she said, explored the technique to understand simple commands.

"The difference with our system is that we can record and recognise continually spoken sentences," said Professor Shultz.

Cebit runs from 2 to 6 March in Hanover, Germany.