Voice quality has to do with voice inflection, cadence, tone, syllabic stress, and other characteristics which convey mood, emotion, and tonal insinuations.
Tone is an art.
Two sentences with exactly the same words, can have entirely different multiple meanings depending on voice tone and quality. Facial expression is perhaps the next most important form of non-verbal communication. Expressions convey the mood and current emotional state of the speaker. Expressions can communicate all sorts of emotions. Kinesics, or the movement of the hands and body also convey information.