When you speak, your voice carries not only your words but how you feel about those words, about your audience, and about yourself. It does so through its prosody, certain attributes that provide a meaning to speech that cannot be supplied through vocabulary and grammar alone.
Prosody may be a term you know from the arts of poetry and music; in linguistics, it's used to refer to the stress, volume, pitch, and cadence of speech. These elements create meaning for both the speaker and the listener—for both speech production and speech reception.
Some prosodic attributes are organic in a particular language or dialect; others are idiosyncratic. Proficient speakers can learn to manipulate almost any of them to clarify or emphasize intended meaning. Such manipulation is essential if you are to avoid the monotonous voice that so many listeners find objectionable.
In oral communication such as a presentation, delivery is prosody.
Speech delivered without variation in stress or tone is boring and gives listeners inadequate signals of emphasis or importance. It suggests to listeners that you have little invested in them or in your message, that you don't really care much whether or how your listeners respond.
As you speak, follow the stresses that a word normally contains to make some syllables more prominent than others. But also experiment with stressing certain syllables or words even more strongly to indicate to your audience that they are of special significance.
Consciously changing the volume at which you are speaking prevents your voice from slipping into monotony but also alerts your audience to the nuances of your message. Occasionally lower your volume to stir audience interest or renew its attentiveness. Raise volume gradually as you build toward a point; vary it to signal a change in idea or approach.
As you experiment with volume and its impact, remember that you must always speak loudly enough to be heard. And, while a microphone will amplify it, your voice must still contain the prosodic attributes that audiences use to construct meaning.
Although soundwaves travel through air at a relatively constant speed, the frequency with which they are emitted makes the sound higher or lower. Those that are emitted with great or high frequency make the voice higher; at moments of panic or fear, for example, the voice may become shrill because the soundwave frequency increases.
Become aware of pitch and learn to refine it, phrase-by-phrase. In English, for example, questions end on a note that's higher than earlier parts of the sentence. Declarative or affirmative statements end at a level or slightly lower pitch; concluding them on a higher note makes them sound like questions and are likely to create doubt or misunderstanding in your listeners.
A uniform pitch contributes to monotony. We tend to ignore sounds that recur without variation, so mingle and arrange the notes.
You can alter both the tempo (speed) and rhythm (pattern of sound and silence) of your voice to guide listeners and enrich meaning. To emphasize certain statements or arguments, speak more slowly. Increase speed to show excitement, humor, enthusiasm, anticipation.
Well-placed pauses can help you underscore a major point or transition to another. They can also be used to allow listeners time to absorb complex or controversial ideas.
When you employ these techniques, you demonstrate competence and control, concern and credibility. You move listeners closer to the coherent understanding you want them to form. Perhaps speech prosody is an art, after all?