I kind of hate the voice used for navigation, alarm clock. Seems everything is using that same voice. Too robotic for my liking. I found IVONA Text-to-Speech Voices | TTS Voices | Text To Voice
Not sure how good it is. Is there a better app than Ivona?
Ivona voice sounds the best hands down (especially Amy and the new not yet on Android Salli voice). Works great on all apps for me. Sadly, whenever I reboot phone, Ivona no longer works. Only fix is to reinstall the whole thing which is a total PITA. I still do it though cause it sounds so much better then any of the other choices.
If it's possible, you can update to Jelly Bean (regular or via mod).
Android 4.1 comes with a new Google TTS engine that sounds very natural and IMHO tops SVOX classic (at least the german voice as of Q3/2012).
Included languages so far are:
