How to Deliver Winning Presentations: Using Your Voice to Connect with the Audience 

We've seen that an attitude of appreciation, respect, and enthusiasm is the key to achieving the all-important connection with your listeners. In the last column, we examined ways to express that attitude with your body and face, through appropriate position, movement, gestures, and smile. This time, we'll consider the contribution your voice can make. Briefly, you must be heard and understood; you must talk at the right speed that invites the audience to stay with you; and you must maintain an emotional bond by expressing appropriate emotions.

Reimold, Cheryl. IEEE PCS (2000). Articles>Presentations>Advice>Emotions