Hearing loss has many causes, which might explain why it is so poorly understood. For example, not all people with hearing loss have the same type of hearing loss. Some are born with it, while others develop it as they age. Others lose their hearing from exposure to loud noises or infections. 

To set the record straight, we look at some of the most common causes of hearing loss.

Getting older

This is the most common cause of hearing loss worldwide.

A declining sense of hearing is a natural part of aging, as many of our systems experience wear and tear over time. Ask many people over 65, and they'll tell you that age-related hearing loss (other known as Presbycusis) currently affects them, or they are on the watch for symptoms. Presbycusis affects one in three people over 65 and almost half the population over 75 years old. However, it can be tricky to pinpoint when hearing loss begins and why.

Age-related hearing loss happens when the delicate nerves in the inner ear start to show signs of aging. The most common cause of age-related hearing loss is a loss of function in the inner ear, but the middle ear can also lose function. A complicated network of nerve pathways between the ear and the brain can be cut off. 

All this means is that hearing is a symphony, not just a single tune and that aging can change many complicated parts that work together to make hearing work well.

Noise exposure

Noise Induced Hearing Loss (NIHL), caused by overexposure to loud noises, is one of the most prevalent causes of hearing loss. A night out with friends at a packed sports stadium, blowing off fireworks, or even sanding the back porch may all be detrimental to your hearing health. 

Noise-induced hearing loss causes difficulties hearing background noise and loss of spoken sound quality. Along with NIHL, many patients have tinnitus, a bothersome ringing or buzzing in the ears that may prevent you from obtaining a good night's sleep. Vertigo and balance issues are also common adverse effects of noise-induced hearing loss.

Complications from illness

A variety of infections can often lead to hearing loss, including:

• Meningitis: Recovery from bacterial meningitis can take a long time and often can lead to long-term complications, such as hearing loss or brain injury.
• Measles: The CDC reveals that in about 1 in 10 measles cases, ear infections occur, which carries the risk of irreversible hearing loss. Hearing issues arise because measles affects the brain's nerves - a disorder in which brain swelling occurs.
• Flu: Congestion builds up in the middle ear when you have a cold or flu, which makes it harder for the sound waves to pass through the ear. In certain sporadic cases, the flu virus can affect the nerves in the ear and cause irreversible damage to the hearing.

Painkillers

We all keep Tylenol or Advil in the cupboard to alleviate headaches or flu symptoms. While a few painkillers now and then won't hurt, the American Journal of Epidemiology recently published a study that showed that regular use of these over-the-counter painkillers could increase your hearing loss! As a side effect, these drugs reduce blood flow to the ears, depriving the ears of oxygen and leading to cell damage.

Head trauma 

Traumatic brain injuries have been in the news a lot lately. There are risks immediately during and after an injury or concussion, but there can also be long-term effects. 

Each feature within the ear works to remain sensitive to the nuanced differences in sound, making it susceptible to damage. Take, for instance, the tiny hairlike organelles of the inner ear called stereocilia. These tiny cell clusters detect the slightest difference between sounds, making it possible to tell the difference when a person uses a unique tone of voice or has a regionally derived accent. These subtleties also make the stereocilia quite prone to damage. 

When a person has a head injury, the impact can commonly lead to a flush of fluid, bone, or other pressure into the ear canal or inner ear, causing damage to the components. This head injury might affect the brain, but the direct effects on the ear cannot be ignored. Some head injuries, including traumatic brain injuries, can cause damage to the auditory nerve pathway or even the brain's auditory cortex. 

Inherited hearing loss

According to the National Institute on Deafness and Other Communication Disorders (NIDCD), about "2 to 3 out of every 1,000 children in the United States are born with a detectable level of hearing loss in one or both ears." If a child is born with hearing loss, the condition is called congenital hearing loss.

Congenital hearing loss differs from acquired hearing loss, which occurs at any time after birth. Congenital hearing loss may be caused by genetics, infection during pregnancy, or premature birth, among other health conditions. Genetic factors cause approximately 50% of hearing loss cases in children.