The sound you hear is actually being generated by the part of your ear known as the cochlea. It’s a very complicated organ with sensory hairs, internal fluid and nerve receptors, that when damaged (or as it naturally degrades as you get older), can cause it to send incorrect input into your brain. In layman’s terms, because it’s no longer working as well as it used to, it thinks there’s a ringing sound in the area and tells your brain to generate that sound in your head. There are other symptoms of tinnitus, but this is the main one.
Tinnitus masking or noise suppression devices are common treatment options for tinnitus sufferers. This type of device is worn in the ear like a hearing aid and produces either a constant signal or tonal beats to compete with the sounds you're hearing. The hearing care professional will use the pitch matching and loudness matching tests to set the signal at a level and pitch similar to the tinnitus you are perceiving.

However, the multidisciplinary approach based on CBT is not a “cure for tinnitus”, as implied in some papers, but rather a system for managing its symptoms and effects on people’s lives. The differences in outcomes between the treatment and usual care groups were quite small, with the multidisciplinary approach giving a small improvement in quality of life compared with usual care, and moderate improvements in tinnitus severity and impairment. Also, less than 70% of participants completed the trial to 12 months, and this could have affected the reliability of the study’s overall results. Furthermore, as the patients in the study were only followed for 12 months, it is uncertain whether this approach can help in the longer term.

Earwax (ear wax) is a natural substance secreted by special glands in the skin on the outer part of the ear canal. It repels water, and traps dust and sand particles. Usually a small amount of wax accumulates, dries up, and then falls out of the ear canal carrying with it unwanted particles. Under ideal circumstances, you should never have to clean your ear canals. The absence of ear wax may result in dry, itchy ears, and even infection. Ear wax may accumulate in the ear for a variety of reasons including; narrowing of the ear canal, production of less ear wax due to aging, or an overproduction of ear wax in response to trauma or blockage within the ear canal.
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.