You may want to check Recognito that does text independent speaker recognition in Java
It's a FOSS lib licensed under Apache 2.0
https://github.com/amaurycrickx/recognito
disclaimer: I'm the author :-)
It has a light dependency on Oracle's javax.sound for file handling but it should be straightforward to remove this dependency from the main Recognito class (a few methods to discard: look for "file" in params and hit del)
I'm not aware of any other FOSS alternatives that would be Android compatible without modifications
There's plenty of javadoc, the code should be straightforward.
The one thing you'll wonder is how to create the double[] with values between -1.0 and 1.0
For a start you may want to look at FileHelper class which does just that with a 16bit PCM encoded file.
Please note a single word won't suffice to extract a good vocal print and to recognize the user afterwards
For the process, I'd say use a phrase repeated 3 times to build an averaged vocal print. Use the same phrase at recognition time.
The lib is text independent but it will help to use the same phrase if you need to keep the recording short. If you want it truly text independent (user says anything and gets recognized), you'll need longer vocal samples.
HTH
