Researchers at Germany's Karlsruhe Institute of Technology (KIT) have developed a method for mobile phones to convert silent mouth movements into speech. The technology is based on the principle of electromyography, that is the acquisition and recording of electrical potentials generated by muscle activity. This muscle activity is measured in the face and converted into speech.

An example is soundless calling.

The user can speak into the phone soundlessly, but is still understood by the conversation partner on the other end of the line. As a result, it is possible to communicate in silent environments, at the cinema or theater, without disturbing others. Another field of use is the transmission of confidential information.