You may be able to install this via package manager, but I built the shared lib from source

espeak-ng

sudo apt-get install espeak-ng-espeak 

Not sure on the diff, but espeak (no -ng) was available for cygwin package management.

Using it required removing -ng from the link in the g++ command and include in speechsynth.h

When I use it on linux, it has some noise about my sound card printed to stdout/err, but other than that seems to work fine

sudo apt-get install libespeak-dev

sudo apt-get install libncurses5-dev

using makefile for now

make && ./bin/app

or

make && gdb bin/app