Another way to do this would be to offload the speech synthesis from the mcu, and thus also remove the need of a library by using a synthesis chip. So you could still easily use an msp430 and its low power feature, while having nice sound, and it would be very easy.
Edit : Also, if you want to practice your electronics skill related to embeded system, and not your math skill and university level algorithmic skill, the synthesis chip will be a better idea, it would introduce you to reading datasheet, interfacing chip, using i2c, spi, uart or i2s depending on the chip. Those are communication protocol widely used in electronics and robotic to interface component.
What research have you done so far? We can't help you if you don't make some effort/give more detail. You just come here and say "i want to do this"... Sorry, but you need to provide us more information if you have done some research or you have to start doing some research on your own. From the number of post, and the way you ask for help, I understand you are pretty new to this forum, but also programming/embedded system(by the simplistic way you put out your project).
For example, is there are any library you would like to use? (I mean, what library you have found so far to do this). If we know which library, it would be easier to see how to port it. Also, you know this is a msp430 forum. So you should either tell us which micocontroller you want to use if its not an msp430, or review the strength of the msp430. msp430 is not a good mcu for the workload you want to do. In fact, the msp430 has the same amount of power, or even less(because of multiple cycle per instruction), than an AVR (8 bit). The only difference is that it has native 16 bits arithmetic. To do digital synthesis of voice, you will need lot of power, either an arm cortex or a DSP.
So here what you should do:
- Go check what are the currently existing library for this, or ask around for which library exist (sorry, i don't know too much about this)
- Try to find out which mcu you want to use, and do some research on it to see if it has enough power to handle this
Here what mcu you should looking for : 16 bit with DSP (C2000, dspic) or 32 bit power (ARM cortex, blackfin, pic32, and many more). If you take 32 bits path, i suggest you look for one with floating point. Also, if you take the right microcontroler, there is a high probability that there is a library for it available to do what you want. (more chance to find a DSP related library on a DSP architecture or a beefy architecture).
Also since you are new to all this, I suggest you stay with simple architecture. So either go with dspic, pic32, or to some extent, the tivaboard. (The tivaboard has a tiva mcu, which is an arm cortex. The only advantage it has is the IDE and energia, but you better stay out of this for now). Another possibility would be to use something a little bit highter level, to simplify all this. You could use a raspberry PI or an mbed (this is a platform similar to arduino, but with much more advanced capability). All mbed use an arm cortex, i don't know if you will find a library for this on the mbed, but it cost nothing to check this out. There are many cheap mbed platform, and mbed is easy to use. Nucleo and freedom board to name a few (around 10-20 $ board). Myself, i ordered a mbed recently, to check this out.
With mbed, you have almost full power on the mcu (except at the interrupt level), whit out having to know the inner-working of the mcu.