13. Speak expressively.
If you want to sound smart, avoid speaking in monotone.
According to Leonard Mlodinow, author of "Subliminal: How Your Unconscious Mind Rules Your Behavior," "If two speakers utter exactly the same words, but one speaks a little faster and louder and with fewer pauses and greater variation in volume, that speaker will be judged to be more energetic, knowledgeable, and intelligent. Expressive speech, with modulation in pitch and volume, and a minimum of noticeable pauses, boosts credibility and enhances the impression of intelligence."
Over at Inc., Geoffrey James suggests that you "slow down and speed up depending upon the importance of what you're communicating at the time. If you're summarizing or going over background, speak more quickly than when you're providing new information. When you're introducing an important concept, slow down to give listeners time to absorb it."