Final answer:
The Korotkoff sound corresponding to the systolic blood pressure is the initial soft ticking or tapping noise heard through the stethoscope during blood pressure measurement, indicating the resumption of turbulent blood flow through the brachial artery.
Step-by-step explanation:
A medical assistant would describe the Korotkoff sound that corresponds to the systolic blood pressure as the initial sound heard through a stethoscope when using a sphygmomanometer to measure blood pressure. This sound is characterized by a soft ticking or tapping noise that represents the turbulent blood flow resuming through the brachial artery as the cuff's pressure is lowered and becomes equal to the systolic pressure. The onset of this Korotkoff sound signifies the systolic blood pressure measurement, which is the maximum pressure in the arteries when the heart contracts.