Parkin's Lot: Gender of voice-over and e-learning effectiveness
Some gender stereotypes affect the perception of voice over, but gender is likely not the most important characteristic for retention. This post is older and not all the links to citations work
But most <a href="http://www.mtholyoke.edu/courses/lablouin/psych200/project_fall01/narrator.htm">studies</a> that I have seen indicate no statistically significant difference between retention by an audience of one gender of content delivered by a voice of another, or the same, gender.
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<br>In my experience there are characteristics other than gender that play a much bigger role in engaging a learner audience. Things like dynamism, clarity, 'emotional bonding' with the content, enthusiasm, and perceived subject matter expertise are more important than whether it is a male or a female voice.