What Causes Deafness? From Birth Conditions to Later-Life Hearing Loss

Hearing loss and deafness happen for many different reasons. To understand what causes deafness, we can group the causes into two main types. The first type is called congenital, which means the hearing loss is there when a baby is born or happens shortly after birth. The second type is called acquired, which means the hearing loss develops sometime after birth. Congenital causes are usually related to genes or problems during pregnancy and birth. Acquired causes can happen for many reasons, including infections, being around loud noises, getting older, and injuries. Finding out the specific cause of someone's hearing loss is very important for figuring out the best ways to help them. This guide explains these causes in simple terms for anyone who wants to learn more.

Causes Present from Birth

When we say congenital, we mean that a hearing problem exists from the moment a baby is born. These causes are responsible for most of the hearing loss found in babies and young children. We can divide them into two groups: genetic factors, which are passed down from parents, and non-genetic factors, which usually happen because of problems during pregnancy or birth. For parents and families, understanding why their child has hearing loss can help them better understand their child's health and future care needs. It helps make the condition less confusing and gives them a good starting point for talking with doctors about what might happen next and what treatments might help, such as hearing aids, cochlear implants, or speech therapy.

Genetic Factors

More than half of all hearing loss present at birth comes from genetic factors. These are passed down through families, even when the parents can hear normally. Genetic hearing loss comes in two main types. The first is called syndromic hearing loss, where deafness happens as part of a larger medical condition that includes other symptoms. Examples include Usher syndrome, which causes both hearing loss and vision problems that get worse over time, and Waardenburg syndrome, which can cause hearing loss along with changes in the color of skin, hair, and eyes.

The second and more common type is called nonsyndromic hearing loss. In these cases, hearing loss is the only medical problem. The person is healthy in every other way. Scientists have found hundreds of different genes connected to deafness. Changes in the GJB2 gene are a very common cause of nonsyndromic hearing loss in many people around the world, showing how complex the genetic instructions are that control our ability to hear.

Non-Genetic Factors

Not all hearing loss present at birth is inherited from parents. Many cases happen because of non-genetic factors related to the mother's health during pregnancy or problems during birth. These events can interfere with how the hearing system develops in the baby.

• Infections that the mother gets during pregnancy can affect the developing baby. Viruses like Rubella (German measles), Cytomegalovirus (CMV), herpes, and infections like toxoplasmosis are known to increase the risk of hearing loss.
• Being born too early (premature) and having a low birth weight are also linked to a higher chance of hearing loss. Babies born too early may have hearing systems that are not fully developed and are easier to damage.
• Birth asphyxia is a condition where a newborn does not get enough oxygen during birth. This can damage many parts of the body, including the delicate parts of the inner ear and the hearing nerve.
• Severe jaundice in newborns, if not treated, can lead to high levels of a substance called bilirubin in the blood. This substance is harmful to nerve cells, including the hearing nerve.
• Certain medications taken by the mother during pregnancy can also affect the baby's development and lead to hearing loss.

Causes That Develop After Birth

Acquired hearing loss means any hearing loss that happens after birth. It can develop at any age, from childhood to old age, and it is the most common type of hearing loss overall. The reasons for acquired hearing loss are very diverse, ranging from infections and loud noise exposure that can be prevented to injuries and health conditions that cannot be avoided. Understanding these different causes is important because it can help people take steps to prevent hearing loss and recognize the warning signs early. The following sections explain the most common types of acquired hearing loss, including infectious diseases, physical injuries, and side effects from certain medications.

Infectious Diseases

Certain infections, especially those that are not treated quickly or properly, can lead to permanent hearing loss. They can damage the delicate parts of the inner ear or the hearing nerve that sends sound signals to the brain.

• Meningitis is a serious infection that causes swelling of the membranes around the brain and spinal cord. It is a leading infectious cause of acquired deafness, especially in children.
• Viral infections like measles and mumps used to be common causes of hearing loss, but they happen much less often now because of vaccines.
• Chronic ear infections, known medically as otitis media, are very common in young children. If these infections happen often or last a long time, the buildup of fluid can lead to conductive hearing loss, which happens when sound cannot travel properly through the outer or middle ear. While this is often temporary, chronic untreated infections can sometimes cause permanent damage. This is different from sensorineural hearing loss, which involves damage to the inner ear or hearing nerve.

Physical Trauma and Injury

Physical injury to the head or ear can directly cause hearing loss. The damage can be to the mechanical parts of the ear or to the nerve pathways that process sound.

• A head injury, such as from a fall, car accident, or sports injury, can cause a traumatic brain injury (TBI). A TBI can damage the part of the brain where sound is processed, or it can break the delicate bones around the inner and middle ear.
• A perforated eardrum can be caused by a direct injury, such as putting an object too far into the ear canal, or by sudden, extreme changes in pressure, known as barotrauma. This can happen during scuba diving or flying. A loud explosive blast can also rupture the eardrum, which is an example of acoustic trauma. While many perforated eardrums heal on their own, some can lead to complications and hearing loss.

Medications That Can Damage Hearing

Some medications can damage the hearing or balance organs of the inner ear. This side effect is called ototoxicity. The damage can sometimes be temporary, with hearing returning to normal after the medication is stopped, but in many cases, it is permanent. Many drugs are known to have this risk, and they are often used to treat very serious, life-threatening conditions.

• Certain antibiotics, especially a group called aminoglycosides like gentamicin, are well-known for their risk of damaging hearing.
• Some powerful chemotherapy drugs used in cancer treatment, such as cisplatin, can seriously damage hearing.
• High, long-term doses of aspirin and other similar pain relievers can cause temporary hearing loss and ringing in the ears.
• Loop diuretics are drugs used to treat heart failure and kidney disease. They can also affect hearing, especially when used at high doses or combined with other drugs that can damage hearing.

It is very important to understand that you should never stop taking a prescribed medication without first talking to your doctor. The risk of hearing loss must be carefully compared against the life-saving or essential health benefits of the medication.

Noise-Induced Hearing Loss

Among all the causes of acquired deafness, noise-induced hearing loss (NIHL) is one of the most common and, importantly, one of the most preventable. It happens when the sensitive structures of the inner ear are damaged by exposure to loud sound. Inside the cochlea, our snail-shaped hearing organ, are thousands of tiny hair cells called stereocilia. These cells convert sound vibrations into electrical signals that are sent to the brain. Loud noise can damage these delicate cells, much like walking on grass can bend or break the blades. Once these hair cells are destroyed, they do not grow back, and the resulting hearing loss is permanent. This damage can happen from a single, very loud sound, like an explosion (acoustic trauma), or more gradually from continuous or repeated exposure to loud sounds over a long period.

How Loud is Too Loud?

To protect our hearing, we need to understand what levels of sound are dangerous. Sound intensity is measured in units called decibels (dB). According to the National Institutes of Health (NIH) and the Centers for Disease Control and Prevention (CDC), long or repeated exposure to any noise at or above 85 decibels (dBA) can cause gradual, permanent hearing loss. The risk of damage depends not just on how loud the sound is, but also how long you are exposed to it. For every 3 dB increase in sound level, the safe listening time is cut in half. The chart below shows everyday sounds and their potential risk.

Practical Hearing Protection

Protecting your hearing goes beyond simply avoiding loud places. It involves developing good habits to manage your sound exposure in daily life.

• Use the 60/60 Rule. When listening with headphones or earbuds, a good guideline is to listen at no more than 60% of the maximum volume for no more than 60 minutes at a time before taking a break.
• Choose the right protection. For noisy environments like concerts or when using power tools, hearing protection is essential. Simple foam earplugs work well and are inexpensive. For frequent exposure, custom-molded earplugs or noise-canceling headphones can provide better comfort and protection.
• Be aware of your environment. Many places we visit, such as gyms with loud music, busy bars, and public transportation, can have dangerously high noise levels. Be mindful of these spaces and take listening breaks by stepping outside or finding a quieter area.

• Advocate for workplace safety. If you work in a noisy industry, your employer is often required by law (like OSHA regulations) to provide hearing protection and implement a hearing conservation program.

Age, Health, and Hearing

Hearing loss is not always caused by a single event that you can identify. Often, it is the result of a combination of factors that build up over a lifetime, particularly the natural aging process and a person's overall health. The inner ear is a complex organ that needs a lot of energy to work properly. It depends on a good supply of blood and a healthy, functioning nervous system. When these systems are affected by age or disease, hearing ability can decline. This section explores how age, diseases throughout the body, and the health of our hearing system are all connected.

Age-Related Hearing Loss

The gradual loss of hearing that happens in many people as they get older is called presbycusis. It is one of the most common conditions affecting older adults. Presbycusis typically affects both ears equally and begins with a reduced ability to hear high-frequency sounds. A person with early presbycusis might first notice difficulty understanding speech in noisy restaurants, or they may find it hard to hear birds singing or a phone ringing. They might frequently ask others to repeat themselves, often feeling that people are mumbling or not speaking clearly. This type of hearing loss is thought to be caused by a lifetime of wear and tear on the hearing system. Being exposed to noise throughout one's life can significantly contribute to and make age-related hearing loss worse.

Body-Wide Diseases and Hearing

The health of your ears is deeply connected to the health of your entire body. Because the inner ear relies so much on a steady supply of oxygen and nutrients from the bloodstream, any disease that affects the circulatory system can also impact hearing.

• Cardiovascular Disease and High Blood Pressure: Conditions that affect blood flow, such as atherosclerosis (hardening of the arteries) or hypertension, can reduce circulation to the cochlea. This can deprive the delicate hair cells of the oxygen they need to function properly, leading to damage and hearing loss.
• Diabetes: Over time, high blood sugar levels associated with diabetes can damage both the small blood vessels and the nerves throughout the body. This damage can extend to the inner ear, leading to a higher risk of sensorineural hearing loss.
• Autoimmune Disorders: In conditions like rheumatoid arthritis or lupus, the body's immune system can mistakenly attack its own healthy cells. In some cases, these attacks can target the structures of the inner ear, causing inflammation and hearing loss.
• Otosclerosis: This is a condition where abnormal bone growth occurs in the middle ear. This growth can prevent the tiny bones responsible for transmitting sound from moving properly, leading to a progressive conductive hearing loss.

Recognizing Signs and Seeking Help

If you or a loved one are concerned about hearing loss, the most important thing to do is take action. The first step is to recognize the common warning signs, which often appear gradually and can be easy to dismiss. Ignoring these signs can lead to delays in diagnosis and treatment, which can impact communication, social relationships, and overall quality of life. Learning about what to look for and what to expect from a professional evaluation can reduce anxiety and help you navigate the path to better hearing health.

Common Warning Signs

Being aware of the early signs of hearing loss is important for getting help in time. Look out for these common signs:

• Frequently asking others to repeat what they have said.
• Difficulty following conversations, especially when two or more people are talking.
• A constant feeling that other people are mumbling or speaking unclearly.
• Needing to turn up the volume of the television or music to a level that others find too loud.
• Experiencing a ringing, buzzing, or hissing sound in the ears, known as tinnitus.
• Finding it particularly challenging to hear in noisy environments like restaurants, meetings, or family gatherings.

The Professional Evaluation

Trying to diagnose hearing problems yourself is not reliable. If you notice any of the signs above, it is important to schedule an appointment with a hearing healthcare professional, such as an audiologist or an Ear, Nose, and Throat (ENT) doctor. A professional evaluation is straightforward and painless. It typically begins with a discussion of your medical history and specific concerns. The professional will then perform a visual inspection of your ear canals and eardrums. The main part of the evaluation is a comprehensive hearing test, usually done in a soundproof booth. This test, which creates a chart called an audiogram, precisely measures your ability to hear different frequencies and volumes. Afterward, the professional will explain the results and discuss the potential causes and next steps.

Taking a Proactive Approach to Hearing

What causes deafness includes many different factors, spanning from our genetic code and the circumstances of our birth to the choices we make and the environments we live in throughout our lives. We have explored the key categories of congenital causes, including genetic and prenatal factors, and the wide variety of acquired causes, such as infections, noise exposure, aging, and diseases throughout the body. An important point is that while some causes are beyond our control, many others, particularly noise-induced hearing loss, can largely be prevented. Taking a proactive approach to your hearing health is one of the best investments you can make in your long-term well-being. Protect your ears from loud noise, be aware of the signs of hearing loss, and do not hesitate to seek a professional evaluation if you have any concerns. Taking action early is key to managing hearing loss and staying connected to the world around you.