Final answer:
The heart sound produced by vibrations within the heart chambers or in the major arteries from the back-and-forth flow of blood is S2 (second heart sound).
Step-by-step explanation:
The heart sound produced by vibrations within the heart chambers or major arteries from the back-and-forth flow of blood is known as a murmur. This is not one of the normal heart sounds (S1, S2, S3, or S4) but is instead an unusual sound that occurs when there is turbulent blood flow within the heart, often due to a malfunction of the heart valves. Heart murmurs are graded on a scale from 1 to 6, with 1 being the least serious and 6 being the most severe. Murmurs can be detected using a stethoscope and may require further medical evaluation.
The standard heart sounds include: S1, which is the first heart sound, or "lub," associated with the closing of the atrioventricular valves; S2, the second heart sound, or "dub," associated with the closing of the semilunar valves; S3, which may be indicative of an abnormal condition such as congestive heart failure if heard later in life, and S4, which may indicate left ventricular failure. Together, S3 and S4 are rarely heard but can be present in certain pathological conditions.