Not to nitpick you to death or get your panties in a twist, but I might suggest that you add a little volume to the voices when you modulate them. Sometimes whether you take liberties with software to modify a human voice or if you're recording from a completely synthetic software to get the "robot" archetype sound, you can lose clarity. A few extra points of volume can help (though I'm sure there are other work-arounds)...
In the case (like so many of us around here) that you're working with Audacity, the other side of the volume setting is a concern for cut-off (where the sound is more than the software or computer can handle. For that, just watch the "waves" in audacity's recording display as you work. You can see when either mic-sensitivity or volume output gets out of hand because the "waves" will actually fill the view for that channel and appear "cut off" with like the tips missing. That's where you can play with the controls to dial it back just a bit.
My point isn't that you did anything bad, but that this little bit of work will REALLY kick your game up a notch. There's a plethora of stuff on Youtube that suggests you can show the same exact story with a crappy visual but excellent audio in one theater and a great visual but crappy audio in another and more customers will watch the crappy visual... Weird, but fairly true in my experience...
Finally, you did good here. I enjoyed it, and I look forward to your next work. I sincerely hope to help, which is why I point out fixes and options rather than just petty complaints... Don't forget to take a moment and breathe between times :) And keep animating...

nice animation, really smooth. wish I could make something like this!

Keep up the great work guys!