Eight new "talking dictionaries" were unveiled by linguists who journeyed to some of most remote corners of the world in search of vanishing languages.

They feature more than 32,000 written words 24,000 audio recordings of native speakers pronouncing words and sentences, as well as photos of cultural objects.

Of the nearly 7,000 tongues spoken on Earth, more than half may be gone by the end of the century.

The talking dictionaries initiative from National Geographic Society's Enduring Voices project is an attempt to prevent these ancient languages being forgotten. In some cases, it is the first time a language has been recorded or written down anywhere.

Dr David Harrison, from Swarthmore College in Philadelphia, US, one of the linguists creating the dictionary, said: "Endangered language communities are adopting digital technology to aid their survival and to make their voices heard around the world. This is a positive effect of globalisation."

Dr Harrison visited language "hotspots" around the world with colleague Dr Gregory Anderson, president of the Living Tongues Institute for Endangered Languages in Oregon, US.

In 2010 the team provided the first documentation of a language known as Koro spoken by only a few hundred people in north-eastern India.

Alfred "Bud" Lane, one of the last fluent speakers of a Native American language called Siletz Dee-in from Oregon, said: "The talking dictionary is and will be one of the best resources we have in our struggle to keep Siletz alive."

Other dictionaries feature Matukar Panau, an Oceanic language from Papua New Guinea which has only 600 surviving speakers. Before the Enduring Voices team began studying it three years ago, the language had never been recorded or written.