In general, I rarely ever hear pre-recorded boarding announcements (although I think they'd help since the GAs can be so difficult to understand sometimes). But the few times I have heard pre-recorded announcements, they're the woman who is heard doing announcements at many airports. Nothing sounds automated.

The only time I've heard announcements that sound truly automated are like what's discussed above - the ones that page a person to return to the security checkpoint or go to baggage claim, etc. And obviously since these involve paging a particular person, they can't be pre-recorded.