It is always good to have a clear Voice Over for your documentary. When using narration during your video, it would be unfortunate if your audience couldn’t understand the point you are trying to get across. That is why, when making your voice over, you must make sure you have a clear voice. PRONUNCIATION is key! Also, you want to avoid a monotone voice. Fluctuation helps set the mood for a documentary. In the end, a documentary is like telling a story, and you want people to listen to what you have to say and pay attention to your message.
Here is an example of a Voice Over that displays excellent fluctuation and pronunciation.