If you grab the training set for CMU-Sphinx, you'll see that the voice actors providing base input are trained to speak that way. At a secondary level, I imagi

If you grab the training set for CMU-Sphinx, you'll see that the voice actors providing base input are trained to speak that way. At a secondary level, I imagine there's a sort of pitch trajectory for a sentence, and if a word or syllable ends too far off that trajectory, the return to the pitch trajectory is fast enough to be easily detectable.