Part 2. What Causes Tinnitus?

It’s a bird, it’s a plane…no, it’s tinnitus. For people who hear phantom sounds without an external noise stimulus, the condition is known as tinnitus. It may occur in short bursts or for long periods of time, but either way, it is a frustrating reality to live with. There are two forms of tinnitus, subjective and objective, though the latter is rare compared to the former. To understand what causes tinnitus, we first have to examine how hearing works.

How Hearing Works

There are three main parts of your ear: the outer ear, the middle ear, and the inner ear. Let’s say someone rings your doorbell on the other side of the house. The sound of the doorbell travels through space and is picked up by your outer ear. These sound waves move through your ear canal where they meet the eardrum, which begins to vibrate from the waves. These vibrations set the ossicles, which are three small bones (malleus, incus, and stapes), in motion to further amplify sound. The sound waves then continue on into the inner ear, to the cochlea, which is filled with a fluid that moves in response to these vibrations. The movement of the fluid sets the inner ear hair cells in motion, which transform the sound waves into impulses that are sent to the brain to be heard as sound.

Damage to Inner Ear Hair Cells

Perhaps the most common cause of tinnitus is damage to inner ear hair cells, whether due to age-related hearing loss (presbycusis) or exposure to loud noise. In either case, damage to inner ear hair cells may trigger them to release electrical impulses to the brain – without the stimulus of external noise – which will be registered as sound by the brain and thus causes tinnitus.

Common Causes of Tinnitus

There is no singular or easily identifiable cause of tinnitus, especially if it is related to hearing loss. Hearing loss is the third most common medical condition in the US, affecting 48 million Americans and a third of people over the age of 65. Age-related hearing loss occurs naturally when our bodies change as we age. At the same time, noise-induced hearing loss, caused by exposure to dangerous levels of sound – whether in a single event or over long periods of time – may occur to anyone, at any age. Many people may remember short-term tinnitus after going to a particularly loud rock concert or standing too close to fireworks going off. Long-term exposure to loud sounds may cause permanent hearing damage, which may also lead to tinnitus.

In some cases, blockage or damage to different parts of the ear may cause tinnitus. Earwax buildup in the ear canal may lead to tinnitus, as well as hearing loss. Head or neck injuries, temporomandibular joint disorders (TMJ), as well as tumors, may also lead to tinnitus. Medication may also cause tinnitus: certain kinds of anti-cancer drugs used in chemotherapy, classes of antibiotics, and classes of diuretics are ototoxic and cause permanent damage to inner ear hair cells. Additionally, diseases such as Meniere’s or otosclerosis, which affect structures of the middle and inner ear have been linked to tinnitus.

Is there a way to stop the ringing? In our final segment, learn about treatment options for tinnitus.