Why Is the Change in Sound Made by a Passing

question 19

Multiple Choice

Why is the change in sound made by a passing train's whistle similar to the reason the pitch rises quickly in systole and drops quickly in early diastole when measuring arterial sounds?

• A) Both are explained by B-mode ultrasonography.
• B) Both involve the science of plethysmography.
• C) Both are explained by the Doppler effect.
• D) Both are explained by the science of atomic behavior in a strong magnetic field such as MRI.