One of the worst things you can do as a speaker is to speak in a monotone, which will bore your audience and make them lose interest. To keep them engaged, you need to vary your pitch, pace, and volume. Pitch is the highness or lowness of your voice, and it can express different emotions and meanings. For example, you can use a higher pitch to show excitement or surprise, and a lower pitch to show seriousness or authority. Pace is the speed of your speech, and it can affect the mood and energy of your presentation. For example, you can use a faster pace to show enthusiasm or urgency, and a slower pace to show importance or emphasis. Volume is the loudness or softness of your voice, and it can influence the attention and response of your audience. For example, you can use a louder volume to show confidence or passion, and a softer volume to show intimacy or curiosity.