Espeak is a free text to speech synthesizer. It was developed by Jonathan Duddington and its development has stopped in 2015. In 2015 Reece Dunn has taken a copy of espeak and together with a group of developers they maintain and actualize their version of espeak which they call "eSpeak NG". eSpeak NG uses formant synthesis. Currently it supports 100 languages with varying quality of the voices. The current version of eSpeakNG incorporated in Praat is 1.49.3-dev.
The wikipedia page https://en.wikipedia.org/wiki/ESpeakNG gives more details.
© djmw, November 1, 2017