Do you wish your characters could really speak?
For the first time, you CAN!
You can get the extension here, and everything you need to know is right here on the SAMMY website!
This audio illusion is based on the principles of ‘formant synthesis’, where multiple sounds called ‘formants’ are layered to synthesize a human voice.
So the formants making up ‘m’ ‘a’ ‘k’ and ‘e’ are about the same every time you say them, cutting out the need to record audio or store massive amounts of data. SAMMY can speak with just 3 sine waves at a time!
SAMMY (Short for Software Automatic Mouth Makecode Yippee) can speak whatever your heart desires! You can either program sounds in manually or use the automatic generator on the website, then SAMMY will do the rest.
Blocks
Say
Make SAMMY say anything!
The function takes a two-dimensional number array as an input!
What does this mean!?
The function takes one array as its unput. Each value of that array is another array with two numbers. The first number determines the sound SAMMY will make, while the second determines how long he holds the sound for.
The block will then play the sound until done. More info on the inputs to this function are available in the how-to section of the website!
Notes
This project has been in the works for quite a few years now, on and off, and I’m happy I was finally able to polish it and make a tool to hopefully make it easier to use. 
I’d like to thank other users who have experimented with formant synthesis like @chembot @richard and @BLADEr , the moderators (of course!), and @unique for running the UAT2 where SAMMY began. This extension wouldn’t have been possible without their help and the rest of the forum’s overwhelming support for the project! 
I’d be happy to answer any questions you have, fix any bugs, or see what you make!!
– Randomuser / Dragondoodle