Ringing in ears is a medical condition called tinnitus, where the volume heard ranges between persons. It is best described as a perception of sound when none is present. Sometimes the noise is described as hissing, roaring or whining. Tinnitus could be caused by microscopic changes in nerve endings of the hearing nerve that transmits signals from the inner ear to the brain. Check out http://www.livestrong.com/article/253030-causes-of-ringing-in-my-ears/.