I have a potential customer who is currently using SIRI on Apple devices to convert TXT to Voice. They love the ET1 and would like to have the capability.
Knowing that we do not support Google:
Bill try Ivona: http://developer.ivona.com/
They offer cloud and native solutions. I have not personally tried this, but from what I read looks very promising. Remember just because we do not include Google Play, it does not mean you still cannot install apps that are on Google Play by getting a hold of their APK, etc.
interesting round-up: http://www.geoffsimons.com/2012/06/7-best-android-text-to-speech-engines.html