Script analysis will reveal this. Pitch is the level of sound in a character's voice, high, low, or monotone, which may differ from the actor's normal voice. Tape recording the actors will help limit tendencies toward monotone performances. Volume is the inflection, raising and lowering, of the voice to convey the character's emotional intent. Rhythm and tempo are the flow and measurement of syllables, words, speech, and movement of verbal and non-verbal communication together creating the mood, not only of the character, but also of the scene.
Quality is the diction, delivery, and sound characteristics graveliness or smoothness.
Articulation is the formation of words a key to clarity and an indication of the character's roots, history, education, and other background characteristics, such as accents that reveal geographic identity and culture. Like quality, it is important for the actor to remain consistent throughout the performance. This can be difficult if the actor is portraying someone distinctly different from him or herself. Projection is getting the voice to carry without yelling. It is as much an expansion of the full diaphragm as the sound of the voice.