Rather than operating separately, all the vocal elements described so far—volume, pitch, rate, and pauses—work together to create an effective delivery. Indeed, the real key to effective vocal delivery is to vary all these elements with a tone of enthusiasm, thereby producing vocal variety. For example, as King speaks the words “I have a dream,” the pauses are immediately preceded by a combination of reduced speech rate and increased volume and pitch—a crescendo, you might say. The impact of this variety leaves an indelible impression on anyone who has heard his speech.