Tinnitus refers to a ringing or other noise in the ears. It may affect one or both ears. In most cases, the sound is subjective. This means only you can hear the ringing. You may hear it even when your environment is silent.
Around 15 to 20 percent of humans have this condition.  While it can affect anyone, it is more common in adults. Tinnitus is not a disease by itself but a symptom caused by other conditions. This article discusses the symptoms of tinnitus and the possible causes of this problem.
Symptoms of Tinnitus
The main sign of tinnitus is a ringing noise in one or both ears in the absence of external stimulation. Other sounds you may hear instead of this ringing noise include: 
These sounds may be dull or loud enough to distract you from being able to perform a task or listen to external sound.
What Causes Tinnitus
Tinnitus is often indicative of underlying conditions. According to the American Tinnitus Association, there are about 200 causes of tinnitus.  Some known causes are listed here but only a qualified physician can give you an accurate diagnosis. Do not self-diagnose.
Age-Related or Noise-Induced Hearing Loss
Many people experience some form of hearing loss as they grow old. It usually starts around the age of 60 and is often bilateral. While there are several reasons this happens, some have to do with sensitive hair-like cells in the inner ear. 
The inner ears contain a group of hair cells that move when sound waves enter the ear. The motion of these cells sends electrical impulses to your brain via the auditory nerve. Your brain then interprets these impulses as sound.
These hair cells may suffer damage as you age or if you spend many years being exposed to loud sounds. A single exposure to traumatic noise can also cause this damage. When the cells break or bend due to these issues, they may begin sending random electrical impulses to your brain even when there is no external sound. This is known as tinnitus.
Excess earwax and fluid buildup caused by ear infections may block your ear canals. This can increase the pressure in your ears and cause you to hear ringing noises.  Several things besides earwax and ear infections can block the ears and cause tinnitus. A common cause is water that enters the ears while swimming or taking a bath.
If your ears are blocked by earwax, you should see a healthcare professional to help you remove the wax. Sometimes it is possible to do this yourself using ear drops that melt the wax. If the blockage is caused by an infection, treating the underlying infection is the best way to get long-lasting relief.
Meniere’s disease is a disease that affects the inner ear. It is caused by abnormal pressure in the inner ear. Sometimes tinnitus is an early sign of this disease. 
Several symptoms are associated with Meniere’s disease, including tinnitus and dizziness. Meniere’s disease is a serious condition that is marked by a progressive loss of hearing that may affect one or both ears. It is more common in only one ear.
Changes to Ear Bone Structure
As some people age, the bones of their ears may change. The bones in parts of their ears may stiffen and impair normal hearing. The stiffening of these bones is called otosclerosis. Tinnitus is a common symptom associated with this condition. 
Otosclerosis is a hereditary disorder that causes progressive hearing loss and eventually leads to deafness. If you have family members with this condition, it may be the cause of the ringing in your ear.
Some drugs are ototoxic. Ototoxic means the drugs can impair the function of hearing organs. Some ototoxic drugs affect even the auditory nerve. Ototoxic drugs often cause or worsen existing tinnitus. The level of ringing in your ear is sometimes proportional to the dosage of these drugs you use.
Medications that are considered ototoxic include some diuretics, nonsteroidal anti-inflammatory drugs, antibiotics, antidepressants, anticancer drugs, and quinine-based antimalarial drugs. In most cases, the ringing in your ears clear once you stop using these drugs. According to the American Tinnitus Association, some ototoxic drugs cause permanent ear damage. 
If your suspect medication is the cause of your tinnitus, discuss it with your doctor. They may take you off your medication, adjust your dosages, or swap them for better alternatives.
Trauma to the head or neck can affect the brain, inner ear, or auditory nerves and cause you to develop tinnitus.  This problem usually only develops in one ear, on the side impacted by the injury.
If you develop tinnitus after an accident or sporting injury, make sure to let your doctor know. They will then decide the best way to manage or resolve the problem. If the trauma caused a serious internal ear injury, letting your doctor know about your tinnitus may help them discover it.
Inner Ear Muscle Spasms
Less frequently, tinnitus is caused by sudden spasms in the inner ear muscles.  Most times the cause of these spasms is not clear. Sometimes these spasms are indicative of neurological diseases like multiple sclerosis. In addition to hearing loss, ear muscle spasms may also cause temporary hearing loss.
Temporomandibular Joint Disorder
The temporomandibular joint (TMJ) connects the lower jaw to the skull in front of the ears. Damage to the cartilage or ligaments in this joint may cause tinnitus because of its proximity to the ears.  It shares some nerves and ligaments with the middle ear.
Tinnitus caused by TMJ disorder will usually disappear once the disorder has been addressed. Other common symptoms of TMJ disorder are jaw pain, limited range of motion in the jaw, and popping sounds when eating.
Tinnitus usually goes away when the underlying cause is treated. If you have this problem, you should see your doctor for a diagnosis. In cases where the underlying cause is untreatable, your physician may show you ways to manage the condition.