How can problems in the outer ear reduce hearing?

Problems in the outer ear reduce hearing by obstructing the external auditory canal, which prevents sound waves from reaching the tympanic membrane. This impairment occurs through several mechanisms:12

• Obstructions: The canal can become filled with earwax (cerumen), infected material, or tumors, effectively blocking the passage of sound.132
• Infections: Conditions such as external otitis can cause swelling and drainage within the canal, which may clog the passage and impair hearing.4
• Congenital Deformities: Some individuals are born with a malformed or absent outer-ear canal. This structural failure prevents sound from being properly conducted to the inner ear, though the hearing nerve itself is often unaffected.5

In these cases, the sound-transmitting function of the outer ear is compromised, leading to conductive hearing impairment. While some obstructions like earwax can be cleared by a physician, other structural issues may require surgical intervention to construct a new canal and tympanic membrane.152