The sound formation based on string vibration is frequent in the living world, for instance the human voice is based on similar principles. The air coming out of our lungs causes the vibration of our vocal cords and by changing their tension we can produce a deeper or higher sound when we sing.
In the left picture our vocal cords vibrate on both sides of the open glottis in our throat when we produce a sound. In the right picture the vocal chords close the glottis.

From early babyhood our vocal cords get longer and then looser, so our voice becomes deeper and deeper.
Everybody has a unique and typical voice and its tone colour is determined by the proportional volume of the upper harmonics. It also helps to identify people according to their voice, for example during a telephone conversation.