Speak up! Your phone is charging

Prototype shows promise.

South Korean researchers have revealed a project they hope could allow mobile phones to be charged by talking into them.

Britain's Telegraph reported that a team led by Sungkyunkwan University's Sang-Woo Kim aimed to convert sound into electrical power.

The sound source could be the device user's voice or "scavenged" from ambient sources around the phone, such as traffic noise, Dr Kim said.

A prototype did not generate enough power to complete a phone charge but researchers hoped different materials would provide the breakthrough to make a practical charger.