human eye can detect sound

The human eye can detect millions of colors and is sensitive to light and sounds. Yes, sound. University research studies show that mild and incidental noises cause the pupils of the eyes to dilate.

According to David Louis’s book of Fascinating Facts, it is believed that this is why surgeons, watchmakers, and others who perform delicate manual operations are so bothered by uninvited noise: the sounds cause their pupils to change focus and blur their vision.

The “millions of colors” that the eye can detect are the three primary colors of red, green and blue and the millions of combinations that result from these three colors. (In 1878, Ewald Hering proposed the theory that the four unique hues of red, green, blue, and yellow form the basis of all colors.)

source : http://didyouknow.org/human-eye-detects-sound/