Washington: A Washington University team has developed a software that enables deaf or hard-of-hearing Americans to use sign language over a mobile phone video link.

The real-time video communication between cell phones, demonstrated for the first time in the country, has evoked tremendous response from the aurally challenged since its posting on YouTube.

"A lot of people are excited about this," said principal investigator Eve Riskin, a professor of electrical engineering at the Washington University (WU).

For mobile communication, deaf people now communicate by using text messages over the cellphone. "But the point is you want to be able to communicate in your native language," Riskin said. "For deaf people that's American Sign Language."

"Video is much better than text-messaging because it's faster and it's better at conveying emotion," said Jessica DeWitt, a WU undergraduate who is deaf and is a collaborator on the project. She said a large part of her communication is with facial expressions, transmitted over the video phones.

Low data transmission rates on U.S. cellular networks, combined with limited processing power on mobile devices, have so far prevented real-time video transmission with enough frames per second that it could be used to transmit sign language.

The team discovered that the most important part of the image to transmit in high resolution is around the face. This is not surprising, since eye-tracking studies have already shown that people spend the most time looking at a person's face while they are using sign language.