Hearing Loss Causes in Adults: What to Know

Hearing loss in adults has many causes. Some hearing loss causes, such as noise-induced hearing loss (NIHL), are preventable. Other causes, such as those inherited from your family, are harder to prevent. If you're experiencing hearing loss symptoms, an audiologist or otolaryngologist can diagnose what's causing your hearing loss and determine what treatment might be right for you.

This article covers hearing loss symptoms, types of hearing loss, and common causes of hearing loss.

How Hearing Works

Ear anatomy is divided into three parts: the outer ear, middle ear, and inner ear. The outer ear's auricle (pinna) is the visible portion of the human ear that's most recognizable. The outer ear has a funnel-like shape that collects sound waves and sends these vibrations into its less visible ear canal.

Ear: Coronal Cross Section

From the ear canal, sound vibrations hit the eardrum. Vibrating sound waves striking the eardrum set tiny bones called auditory ossicles into motion. The three ossicles in the middle ear are named after their distinctive shapes, which look like a hammer/mallet (malleus), anvil (incus), and stirrup (stapes).

The middle ear's stirrup bone connects to the inner ear. After the stapes bone transmits sound energy into the inner ear, noise vibrations are picked up by a snail-shaped organ filled with fluid called the cochlea. Hearing occurs when signals from the cochlea's vibrating fluid are transmitted to the brain via the cochlear nerve, also called the acoustic or auditory nerve.

The Main Causes of Hearing Loss

Loud noises are among the most common causes of hearing loss in both ears. Outdoor power equipment such as leaf blowers, lawn mowers, and snow removers can damage the inner ear and cause permanent hearing loss. Blasting loud music or playing video games at high volume can also cause hearing loss over time.

Aging increases hearing loss risk. Among people ages 65 to 74 in the United States, 1 in 3 experience age-related hearing loss (presbycusis). After age 75, about half of the U.S. population has difficulty hearing.

Viral and bacterial infections can cause unilateral (one ear) or bilateral (both ears) hearing loss. A common cause for sudden hearing loss (especially in one ear) is an ear infection caused by viral pathogens such as:

• Measles
• Mumps
• Varicella zoster virus
• West Nile virus

Below is a brief overview of the four types of hearing loss with their various causes.

Conductive Hearing Loss

Conductive hearing loss occurs when something blocks sound waves from getting to the inner ear. These sound obstructions can be caused by factors such as:

• Fluid in the ear
• Ear infections (otitis media)
• Barotrauma (mismatched inner/outer ear pressure)
• Earwax blockage (cerumen impaction)

Sensorineural Hearing Loss

Sensorineural hearing loss occurs when something damages inner ear structures or prevents the auditory nerves that facilitate hearing from relaying sounds from the ears to the brain. This type of hearing loss can occur gradually or cause deafness suddenly, which is called sudden sensorineural hearing loss (SNHL).

Common causes include:

• Noise-induced damage (acoustic trauma)
• Aging (age-related sensorineural degeneration)
• Injuries (head or ear trauma)
• Ototoxic medications

Mixed Hearing Loss

Mixed hearing loss is a mix of conductive and sensorineural hearing loss. Some people start with one type of hearing loss and develop another later, or their hearing loss results from mixed factors.

Congenital Hearing Loss

Congenital hearing loss is present from birth. It's often associated with the following disorders:

• Usher syndrome
• Treacher collins syndromes
• Microtia (outer ear birth defect)
  

Other Hearing Loss Causes

Other causes of hearing loss include:

• Meniere’s disease (buildup of fluid in the inner ear)
• Otosclerosis (abnormal growth of middle ear's bony tissue)
• Acoustic neuroma (tumor affecting inner ear nerves)

How Loud Is Too Loud?

One decibel (dB) is one-tenth of a bel. These units of measurement gauge the loudness of sounds. Sounds above 130 dB are very dangerous and can cause instant hearing loss. Any sound or noise above 120 dB can cause harm to your ears and may cause hearing loss in less than 30 seconds. Prolonged exposure to noise or music above 70 dB can damage your hearing over time.

Below is a decibel chart that ranks the intensity of different noises from 20 to 200 dB.

Time Limits for Loud Sounds

Below is information on how long you can be exposed to different decibel levels safely (without hearing protection).

How to Prevent Hearing Loss From Loud Noises

Some tips for preventing hearing loss from loud noises are:

• Avoid loud noises whenever possible.
• Wear hearing protection when using leaf blowers, at concerts, etc.
• Don't blast music for extended periods.
• Set limits for your smartphone's volume.
  
• Get your hearing tested regularly.

Summary

Hearing loss has four main causes. The best way to protect your hearing as you age is to avoid overexposure to loud noises above 70 decibels. Vaccinations are the best way to protect against viruses that can lead to hearing loss. Antibiotics won't help viral ear infections but can be prescribed by a healthcare provider if a bacterial ear infection doesn't clear up on its own.