It's important to keep in mind that Google Text-to-Speech is not compatible with all the apps available for Android – in fact it only works with a few. Among the most important, two are from Google: Google Play Books and Google Translator. The first lets you listen to all the books on your device, and the second lets you listen to the translations.
To activate the voice, you have to follow these steps: access the settings, choose Language and Text Input, and select Google's text-to-speech engine as your default.
Requires Android 4.0.3 or higher