Emotion is an integral component of human speech, and prosody uniquely represents the expressive meaning that is fundamental to communication. In this study, we demonstrate how the subtle and finely differentiated meanings permeating spontaneous speech are communicated by prosodic variations and show that it is the differences in shape that communicate the degree of uncertainty or certainty with respect to the speaker’s knowledge state, specific emotional states, the intensity of emotion, and the effects of other co-occurring emotions.