There are components that affect the speech timing on the S&T board - I had 2 EBD's side by side and one was just slower by a bit and it drove me crazy because it wasn't how I 'remembered' EBD being - that's the one that got sold, and the other one happily is pitched 'better' to my ears. Possibly the differences are down to something like this.

Now, what those components ARE is a good question. If it's the actual TMS5200, you might be out of luck unless you can get a bunch of those to swap. Someone at some point should figure out how to mod the sample data to work with the more readily obtained TMS5220.

I figured that the chip had a lot of analog circuitry in it so that accounts for the variations. Good to know on R9 in case I run up against it again.

It really grated on my ears to hear that slow EBD speech.