After updating to OS X 10.10.2, you may find that VoiceOver will not announce all characters when entering text.
Typically, there are 3-4 characters which VoiceOver does not announce after they have been typed.
There appears to be no pattern as to which letters will be effected.
This behaviour has been encountered with various TTS voices.
Went away, then returned
Deleting and redownloading the TTS voice had fixed this problem for me. However, it’s come back again after a few weeks, but now with a different set of letters not being announced (i, d and l). It’s only for lower case right now. For what it’s worth, I’m using the Ava voice.
All quite frustrating, really.