Articulation, voice volume, speed, all tools to make your story reach the audience more clearly. Silence, between words or sentences, can give so much more meaning to the message you have. Shouting requires attention, but you demand attention if you speak clearly and distinctly. By completing your sentences, down to the last word, the importance of saying these sentences becomes clearer to the audience.
You can distort your voice to play a role. The challenge often lies in being able to keep this up. For a presentation it is especially important that you are understandable. Articulation is more important than voice volume.