The pitch, timbre, volume, speed, and cadence of your voice, the speed with which you speak, and even the way you modulate pitch and loudness, are all hugely influential factors in how convincing you are and how people judge your state of mind and character.

Listeners instinctively detect that when we lower the usual pitch of our voice, we are sad, and when we raise it, we are angry or fearful.

Expressive speech, with modulation in pitch and volume, and a minimum of noticeable pauses, boosts credibility and enhances the impression of intelligence.

Leonard Mlodinow Quotes