Should you be encountering an issue with speech failures on your Fire (or any Android) device, and you are running the Fully Kiosk Browser, with ActionTiles or something similar, please take a look at the Fully Kiosk Browser Controller DTH, for TTS and more.
TTS on my system was constantly failing to speak, now it is 100% reliable, and as an added bonus there appears to be a message queue in Fully, no more chopped messages.