An effective speech should pay attention to how words sound when said aloud. Repetition is often a good thing, but how you say the repeated item brings out the meaning. FYI: Redundancy means to unnecessarily repeat yourself - and that's an entirely different thing. We do not want that in a speech. You'll learn the difference between that and repetition.

Volume, rate, and tone are nonverbal elements of speaking. Words are used, but the message can be changed if volume, rate, and tone are changed. That's why it is nonverbal.

Verbal means words. Verbal does not mean audible (hearable). It means words. A poster with words is verbal. Words do mean things, so consider the connotation of your words carefully when performing a speech.