While tinnitus is as varied as its causes, it can be grouped into two categories: tonal and non-tonal. Tonal tinnitus is more common and describes the perception of a near-continuous sound or overlapping sounds with a well-defined frequency (e.g., whistling, ringing, buzzing). Non-tonal forms of tinnitus include humming, clicking, crackling, and rumbling.
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.
