The observation that one ear opening appears smaller than the other is common, reflecting the inherent anatomical asymmetry present throughout the human body. While often purely cosmetic, a noticeable variation in the size of the ear’s entry point or internal passageway can indicate a structural issue. Understanding the cause of this asymmetry requires distinguishing between differences in the external ear structure and narrowing within the ear canal itself. These variations can be established before birth or acquired later in life.
Understanding the Difference Between the Ear Opening and the Canal
The ear begins with the outer ear, which collects sound. The “ear hole” is the aperture leading into the external auditory canal (EAC), a tube approximately one inch (2.5 cm) long in adults that extends inward to the eardrum. The outer third of the canal is cartilage, while the inner two-thirds are bony. A size difference can originate at the entrance (part of the auricle or pinna) or be due to a narrowing deeper inside, known as stenosis. Constriction in the canal impacts sound wave passage to the eardrum, potentially causing hearing difficulties or increased risk of blockages.
Developmental Reasons for Asymmetry
When an ear opening or canal is smaller from birth, it results from a developmental irregularity during the first trimester of pregnancy. These congenital malformations vary significantly in severity, including microtia (“little ear”), which describes an underdeveloped external ear structure. Microtia often occurs alongside aural atresia (complete absence of the ear canal) or aural stenosis (severe narrowing), as the outer ear and canal develop simultaneously. Congenital aural atresia is most often unilateral, affecting only one ear and creating asymmetry. Children with a narrow or absent canal experience conductive hearing loss because sound waves cannot physically reach the middle ear, though the inner ear is often normal.
Factors That Narrow the Ear Canal Over Time
The ear canal can become smaller later in life due to acquired factors, often stemming from inflammatory tissue reactions triggered by trauma or chronic infection. A common temporary cause is acute otitis externa, or “swimmer’s ear,” where infection causes the soft tissues of the outer canal to swell, reducing the diameter. More permanent narrowing results from the growth of excess bone, known as exostoses or osteomas. Exostoses, often called “surfer’s ear,” occur in individuals with frequent, prolonged exposure to cold water, stimulating the bony walls to grow inward. Other causes of acquired narrowing include post-surgical scarring, chronic skin conditions like eczema, or the formation of a cholesteatoma, a noncancerous skin growth that can block the canal.
When to Consult a Specialist
While a minor difference in ear appearance is harmless, consultation with an otolaryngologist is warranted if the size difference is accompanied by functional issues. Any new or worsening difficulty with hearing in one ear should prompt an evaluation, as conductive hearing loss is a direct consequence of canal narrowing. Recurrent ear infections or a constant feeling of blockage or pressure also indicate a narrow canal may be causing problems. A constricted ear canal can prevent the natural outward migration of earwax, leading to frequent impaction that requires professional removal. The specialist will perform an otoscopy and audiometry test to assess hearing function, and for suspected bony narrowing or congenital issues, a computed tomography (CT) scan may be used to visualize the extent of the constriction before discussing management options.