Arduino can talk without any complicated circuit or extra add thanks to this useful Talkie Library.
Library is working pretty well but adding/converting custom wav files needs some time and knowledge. Discussion is on github.
I've just involved to this conversation issue with my little script to complete a step of complicated conversation steps.
With Freemat; create 10101010101010 (like deladrier on github)
1.step : calc.m
2.step : romgen.m
3.step : with a PHP code I converted this binary snake to Arduino compatible hex format.