If you have enough of a source language and accompanying translation, you can piece back together vital parts of a language if a time comes when it is no longer spoken. Collecting that data can be hard work, however.
To address the difficulties of collecting oral language, Language Preservation 2.0 (lp20) has created Aikuma, a free app for Android smartphones that linguists and community members themselves can use to record language with a function to stop along the way and provide a translation.
Read more about the app, and about Tembé/Tenetehára (tqb) and Usarufa (usa), in the article “Recording the world’s vanishing voices.”
Living Languages 