In NCERT it has mentioned only about 2 heart sounds. But once my teacher said there are 4, can you pls name all

4 heart sounds -

1. First heart sound (S1) -
occurs due to closure of heart valves
low pitched and long lasting

2. Second heart sound (S2) -
occurs due to closure of aortic and pulmonary valves
high pitched, short duration

3. Third heart sound (S3) -
due to turbulence of fluid of rapid filling phase

4. Fourth heart sound (S4) -
due to turbulence of blood during atrial systole
pathological (abnormal) heart sound