Hello,
@turtlepower, I have read on the NVDA forums that the blind extra add-on was marked as unsafe add-on by the community. They stated that the add-on could undertake action on your PC, even as far as sending messages on skype to friends. To be honest, I blocked blind extra from first running on startup, particularly the infovox server, plus I didn't use blind extra for a long time on a daily basis. I even disabled it because it was getting me angry each time I restarted NVDA with popups. So, I'm taking the risk of getting hacked, although I dont know whether it will stay more than five minutes installed on my copy of NVDA.
@Socheat, that's exactly as I have stated in the first post. The acapela voices do not show up, nor have they left any sign of their existance on my NVDA's add-ons or anywhere where they can be found on my system.