An estimated 1.57 billion people worldwide experience some form of hearing loss, according to the Global Burden of Disease (GBD) study conducted in 2019, accounting for one in five people. Projections estimate that by 2050 the impact of hearing loss will reach between 2.35 and 2.56 billion people, a more than 56 percent increase from 2019.

The likelihood of you or someone near you experiencing hearing loss is steadily increasing due to a variety of lifestyle choices, social activities, and natural deterioration related to age. Because hearing loss can have a significant impact on your mental and physical health, relationships, and career, it’s important to develop a better understanding of it.

Warning Signs of Hearing Loss

To begin, here is a quick look at some of the warning signs that you or a loved one could be experiencing hearing loss, like:

If you or a loved one are experiencing one or several of these warning signs, it’s time to take a closer look at what causes hearing loss and begin looking for professional help.

How You Hear Sounds and Speech

Knowing how the process of hearing works is an important part of understanding what causes hearing loss. Here’s a quick look at how you’re able to hear sounds and speech.

There are three main parts along the hearing pathway: the outer ear, middle ear, and inner ear. The outer ear, or ear canal, conducts sound waves to the eardrum, causing it to vibrate.

The eardrum passes the vibrations it receives to three small bones located in the middle ear, which amplify these vibrations and pass them to the inner ear. In the inner ear, the vibrations pass through fluid into a snail-shaped part of the inner ear, known as the cochlea.

Within the cochlea, there are thousands of tiny, hairlike cells that receive the sound vibrations and convert them into electrical signals, which travel along the auditory nerve to the brain, where they are interpreted as recognizable sound.

The Three Types of Hearing Loss

In general, hearing loss involves an interruption of the process somewhere along the hearing pathway. The type and location of the interruption helps define the type of hearing loss.

There are three different types of hearing loss:

Let’s examine the causes and symptoms of each of these types of hearing loss in greater detail.

Sensorineural Hearing Loss: Causes and Symptoms

Sensorineural hearing loss (SNHL), the most common type of permanent hearing loss, affects 85 to 90 percent of adults with hearing loss. It involves damage to the inner ear or the auditory nerve that transfers sound signals to the brain. Damage to the inner ear can be caused by a variety of conditions.

Presbycusis is a progressive bilateral (both ears) type of SNHL that affects adults above 50 years of age. Presbycusis involves the degeneration of cochlear hair cells (stereocilia). Individuals with presbycusis usually experience slowly deteriorating hearing loss associated with a lack of clarity rather than a lack of volume, especially in the presence of background noise. Tinnitus often accompanies this form of SNHL.

The second most common cause of hearing loss is noise-induced hearing loss, which occurs because of damage to the stereocilia inside the cochlea. NIHL can be caused by an extreme noise event like an explosion or due to ongoing exposure to sounds at an unsafe decibel level over an extended period of time.

NIHL affects individuals of all ages due to noise exposure in the workplace, from using certain power tools or lawn and garden equipment, from recreational activities (motorcycling, snowmobiling, hunting, shooting, etc.), or from social activities (concerts, major sporting events, nightclubs, personal listening devices, etc.).

The symptoms of NIHL are similar to those of presbycusis because it is essentially the same type of damage. NIHL is more often accompanied by tinnitus, and in many cases hyperacusis (moderate intensity sounds are perceived as abnormally loud) is also present.

Congenital sensorineural hearing loss is present at birth and is caused either by some genetic deformity or because of an illness during pregnancy. There are more than 400 syndromes that contribute to congenital SNHL, but only a small number of these account for the majority of cases:

- Waardenburg syndrome, the most common

- Usher syndrome

- Pendred syndrome

- Jervell and Lange-Nielsen syndrome

- Alport syndrome

Though presbycusis, noise-induced hearing loss, and congenital hearing loss are the most common causes of SNHL, there are several other traumas or medical conditions that can cause damage to the inner ear, including:

- Head injuries

- Meniere's disease

- Ototoxicity from medicines – aminoglycosides, loop diuretics, some chemotherapeutic agents

- Systemic conditions – meningitis, diabetes

- Vestibular schwannoma (also known as an acoustic neuroma)

- Others – autoimmune, barotrauma, perilymphatic fistula

In addition to difficulties with hearing clarity, those experiencing SNHL may also begin to develop ringing in the ears (tinnitus), dizziness, balance disorders, and/or cognitive decline if the condition is left untreated.

Cause and Symptoms of Conductive Hearing Loss

Conductive hearing loss involves an obstruction or damage to structures at some point along the hearing pathway. The obstruction blocks the conduction of sound signals from reaching the inner ear. It can be temporary or permanent, depending on what causes the obstruction.

Different types of conductive hearing loss and the treatment options available for those experiencing them are characterized by the location of the obstruction and the cause of the obstruction.

Outer Ear Obstructions

Obstructions that occur in the outer ear typically include:

Middle Ear Obstructions

Middle ear obstructions can also interrupt conduction due to conditions like:

Bonus Tip: Dealing With Earwax

One of the most common outer ear obstructions is built up or impacted earwax. Though impacted earwax may be related to many problems, attempting to remove it at home using cotton swabs and other devices is among the most common causes of impacted earwax.

Whenever possible, earwax removal should be conducted by a hearing care professional to prevent the wax from becoming impacted, avoid infections, and prevent damage to the ear canal or eardrum. If you must remove earwax at home, follow these steps:

Symptoms of Conductive Hearing Loss

The typical symptoms of conductive hearing loss involve loudness problems more than issues with clarity. Individuals with this type of hearing loss might turn up the volume on the TV or radio to improve hearing and might experience aural fullness or stuffiness, pain in and around the ears, ringing in the ear, or dizziness and vertigo.

Mixed Hearing Loss: Causes and Symptoms

Mixed hearing loss is less common than either of the other two types, affecting less than 2 percent of individuals with hearing loss. It is a combination of both sensorineural hearing loss and conductive hearing loss, and it can be bilateral (both ears) or unilateral (one ear).

There are only three instances in which mixed hearing loss occurs:

Symptoms of Mixed Hearing Loss

The symptoms of mixed hearing loss depend on the severity of the issue. When examining mixed hearing loss symptoms, it’s best to attribute them to their respective type.

The sensorineural symptoms of mixed hearing loss can lead to: