Tinnitus is when people think they hear something in their ears but there is actually no sound. People with tinnitus actually do "hear" noises that range from a whistle to a crackling noise to a roar. It can happen only occasionally, can occur for a period of days then take a break before recurring again, or it can be constant. The sound can vary in pitch from quiet to unbearably loud, or it can stay the same.
Atherosclerosis. With age and buildup of cholesterol and other deposits, major blood vessels close to your middle and inner ear lose some of their elasticity — the ability to flex or expand slightly with each heartbeat. That causes blood flow to become more forceful, making it easier for your ear to detect the beats. You can generally hear this type of tinnitus in both ears.