yea so you have to assign as i said for each letter detected in the TEXT file you have a "audio file" that sayis something, like A saying "Ah" and then when u play that with audio plugin, you can adjust the pitch speed, etc and make it sound like that... in order to Asign the A to "Ah" b to "bah" etc you have to do the manual work, as there is no library for construct that does that .. plus you will need "custom audio files" it won't sound the same if you pronounce perfectly A but instead you have to pronounce how is heard "A." so ... is a bit of work to be done.
if im not mistaken R0J0hound or dop2000 had some midi player thingie that was assigning .wav recorded notes to some keystrokes on keyboard... that should probably work, you just replace the keys on keyboard with the TEXT detection of the letters that appear in screen.
however the midi file example im talking about is like 3-4 years old example lost to the time in the Construct 2 section, you might be able to find the post if you do a "Construct 2 midi to keyboard player "search something like that..