Why does the soles of your feet make a heavy sound when you only wear socks or walk barefoot?

This is because when the sole of the foot touches the ground, it will produce shock waves, which will make the air and the ground vibrate and form sounds. When wearing shoes, the sole can cushion the impact force and absorb part of the vibration, thus reducing the intensity of sound. Therefore, when wearing only socks or walking barefoot, because there are no shoes to alleviate the impact, the soles of the feet will make a more obvious and heavier sound when they land.