The New York Times wrote recently on the dearth of work for female voice-over specialists. In the industry, men's voices are thought to be more "authoritative" and have more "credibility." (This presumption is a barrier in many employment situations -- eg who gets to make presentations or negotiate prices) Of course no one's really tested the movie voice-over conventional wisdom. You'd just need a controlled study with two identical trailers but for the voice. Anyone offering grant money for that study? No?
In the meanwhile, I chose a female voice -- a close colleague who had worked in radio -- to do the voice-over for a video I produced introducing our new Forum at Harvard School of Public Health. Listen to the results yourself. One small step for womankind.