From a quick glance, it's a very simply a premade wav file which has all letters A to Z with 0.15s for each. The final wav is just a concatenation of all of let

From a quick glance, it's a very simply a premade wav file which has all letters A to Z with 0.15s for each. The final wav is just a concatenation of all of letters from the text, and a silence of each unknown character/space. It doesn't support numbers but could easily be extended beyond what's in the demo. Very clever.