How do I get text to speech to pronounce git and github correctly?

I'm using the OS X text to speech feature for some eLearning stuff. Some of the voices, in particular Lee and Tessa seems to be better quality. However, they mispronounce the words 'git' and 'GitHub'. The American voices pronounce 'git' correctly.

There's already a question regarding pronunciation of 'git' in case you're wondering. It is pronounced with a hard G followed by a short i.

I'm aware that I can modify the pronunciation in the speech settings. However, I have no idea how to set the pronunciation such that it is consistent across all the voices, in particular the non US english voices. Those languages always mispronounce the 'g' of 'git' or 'github'.

I'm running OS X 10.10.2.