Following his customary method, Leonardo has broken down the component organs of the throat to discover the secrets of its functions (breathing, swallowing, phonation), "and then you gradually put them together, so that one can put together the whole with a clear understanding." The most notable studies concern the trachea, larynx, pharynx, and epiglottis. The drawings of the trachea (bottom left, details in the center) and larynx (top left) show that Leonardo analyzes these organs as mechanical instruments. He attributes the production of sounds (phonation) to the turbulence of expired air as it passes through the vocal cords. He compares this phenomenon to the eddies produced by water rushing from a narrow channel into a wider one.