Summary
Hearing loss is a common condition that affects millions of people worldwide. In 2019, an estimated 1.57 billion people globally experienced some form of hearing loss. It can affect people of all ages and can be permanent if not treated correctly. A proper diagnosis involves understanding how the ear works and identifying where the problem lies.
How the Ear Works: Anatomy and Physiology
The human ear is made up of three main parts: the external ear, the middle ear, and the inner ear.
- External Ear: This includes the auricle (the visible part of the ear), the ear canal, and the tympanic membrane (the eardrum). The tympanic membrane separates the external ear from the middle ear.
- Middle Ear: The middle ear is filled with air and contains three small bones called the ossicles: the malleus (hammer), the incus (anvil), and the stapes (stirrup). These bones help transmit sound vibrations from the eardrum to the inner ear.
- Inner Ear: The inner ear is filled with fluid and contains the cochlea, which is responsible for hearing, as well as the semicircular canals, which help with balance. The cochleovestibular nerve carries sound information from the cochlea to the brain for processing.
Sound travels in waves, which are captured by the external ear and funneled to the eardrum. The eardrum vibrates, sending these vibrations through the ossicles into the cochlea. The vibrations create a fluid wave inside the cochlea, which activates hair cells that send electrical signals to the brain, where the sound is interpreted.
Types of Hearing Loss
Hearing loss is typically classified into two types: conductive and sensorineural.
- Conductive Hearing Loss: This occurs when there is a problem in the external ear, eardrum, or middle ear that prevents sound from traveling properly to the inner ear. Many cases of conductive hearing loss can be treated successfully with surgery or other medical interventions.
- Sensorineural Hearing Loss: This occurs when there is a problem with the cochlea, the auditory nerve, or the brain pathways that process sound. Unfortunately, many types of sensorineural hearing loss are permanent because the hair cells in the inner ear have limited ability to repair themselves.
When to Seek Help
If you notice that you or your child is having trouble hearing, it’s important to see a healthcare provider. They can assess the cause of the hearing loss and recommend the appropriate treatment or intervention.
Differentials
Common
- Cerumen impaction
- Foreign body
- Benign tumours (e.g., exostosis, osteoma, polyps)
- Uncomplicated otitis externa
Uncommon
- External ear canal neoplasm
- Necrotising otitis externa
- Tympanic membrane perforation
- Temporal bone fracture

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