Medicine Which of the following is true about fouh hea sound `S4′ : A Can be heard by the unaided ear B Frequency is greater than 20 Hz C Heard during ventricular filling phase D Heard during ventricular ejection phase 💡 Explanation Which of the following is true about fouh hea sound `S4' : ✓ Correct Answer: C. Heard during ventricular filling phase