After listening to Janetta's heart for several seconds, her doctor told Janetta that she has an incompetent right atrioventricular (AV) valve. What did Janetta's doctor hear that led to that conclusion?

Swishing sound.

Explanation:

Human heart produces unique sound when blood flows from one chamber to the next chamber. The two main sounds produced by heart are lub abd dub sound.

The doctor's examine the Janetta's heart and told that she has incompetent right atrioventricular valve. The doctor must have heard the swishing sound after the closing of right atrioventricular valve. This sound is the direct indication of incompetent AV valve.