Any good documentary needs a narrator...if not its just a bunch of pictures and old movies. The narration is what puts you in the time and place shown by the pictures and movies.
Use your own voice...as cheesey as it sound...because you are the one who knows the emotions, the feelings that you are trying to convey to the viewer.
And speaking of cheesy voices, I have read and heard in many documentaries that President Abraham Lincoln had a very high pitched and weak voice and that many who were at the Getisburg Address could not hear a thing he was saying because his voice would not carry more than 15 ro 20 feet from where he was standing.
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