How to Improve Stock Text-To-SpeechThe stock voice for TTS on all Galaxy devices sounds very robotic. Almost unbearable. Luckily, you can make it better by going to the Samsung Apps app that comes with all Galaxy devices and do a search for Samsung TTS. Select the appropriate language that you want to hear, and give it an install.
When you compare it you will hear a world of a difference.
So this change should apply to all apps that requests to use Text to Speech services provided by the Android operating system, including S Voice. Some apps have their own text-to-speech built in and those apps won't be affected.