What gives people a lovely singing voice?
THE GENERAL RANGE of sounds that can come out of your mouth is affffffected by the size of the vocal folds, the strength of your diaphragm and the shape of the chambers in your sinuses. But making this sound beautiful seems to be largely a question of training. At the basic level you must be able to hear a note in your head and reproduce it accurately with your voice. The difffffference between being able to hold a tune and having a genuinely beautiful singing voice is to do with the thousands of tiny and mostly unconscious muscle contractions that subtly adjust the resonant properties of your airway in response to the emotions you feel as you sing. This is the same with any musical instrument. Being born with a wide finger span helps when playing the piano, but the rest is learning the subtleties of timing and pressure on the keys.
Anna Netrebko: nice set of sinus chambers