how does a computer speak?how is it made?

Question

how does a computer produce a human voice?

Answer 1

well, looks like we have multiple ways to achieve human sounding computers. Here's a list
Concatenative synthesis
Unit selection synthesis
Diphone synthesis
Domain-specific synthesis
Formant synthesis
Articulatory synthesis
HMM-based synthesis
Sinewave synthesis

here's the link from WIKI (best site ever)
http://en.wikipedia.org/wiki/Speech_synthesis
it tells all