Microsoft Word Read Aloud function no longer working

I prefer Word's read aloud function to hear my writing assignments spoken to me, because it sounds natural. It is read how it is typed so I can hear how it reads to others. The speech option on my Macbook air is all choppy and there is not a way to adjust the speech rate or the voice. It does not sound how it is written either. There are pauses where there should not be and no pauses where there should be. I have uninstalled Microsoft Office and reinstalled it, but nothing has helped. Can I uninstall updates to get it to work again? I really need that feature when writing college essays. Please Help!