According to Dictionary.com, vocal resonance (from a medical perspective) refers to the sounds that are heard through a stethoscope, when listening to the chest area as a person speaks. Vocal instructor Karyn O'Connor notes that in terms of singing, vocal resonance describes the relationship between the vocal cords and pharynx and the sound it creates. Classical singers enhance their sound through optimal vocal resonance.
Optimal vocal resonance requires an opening of the throat to create positive sympathetic and conductive vibrations between the vocal cords and the pharynx and within the resonant cavities of the vocal tract. Each cavity and the singer's control of the cavity – for instance, by moving the soft palate up and down – is responsible for the pitch and tone of the notes a singer emits.