Why can swelling in the outer-ear canal cause temporary hearing loss?

Swelling in the outer-ear canal can cause temporary hearing loss because it obstructs the passage of sound waves to the tympanic membrane.1

The external auditory canal is responsible for funneling sound waves toward the middle ear, where they are eventually transmitted to the inner ear. When the canal becomes clogged due to swelling—often associated with conditions like external otitis—or by the accumulation of impacted earwax, the physical pathway for sound is blocked. This obstruction prevents sound waves from reaching the tympanic membrane effectively, resulting in impaired hearing. Once the blockage or swelling is cleared, the ear's ability to conduct sound is typically restored.213