Final answer:
The sound heard as a result of the closure of the pulmonic and aortic valves is called the second heart sound (S2) and it is heard loudest at the base of the heart.
Step-by-step explanation:
In a normal, healthy heart, the sound heard as a result of the closure of the pulmonic and aortic valves is called the second heart sound (S2). It is heard loudest at the base of the heart. The pulmonic valve, also known as the pulmonic semilunar valve, closes when the ventricle relaxes and blood flows back into the ventricle from the pulmonary trunk, causing the pocket-like flaps of the valve to fill and produce an audible sound. Similarly, the aortic valve, which is located at the base of the aorta, closes when the ventricle relaxes and blood attempts to flow back into the ventricle, resulting in the production of an audible sound.