Conductive hearing loss is a failure in the efficient conduction of sound waves through the outer ear, tympanic membrane (eardrum) or middle ears (ossicles). This type of hearing loss may occur in conjunction with sensorineural hearing loss or alone.

Causes of conductive hearing loss

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External ear

Common

• Cerumen (ear wax)
• Otitis externa

Uncommon

• Foreign body in the external auditory canal
• Exostoses
• Tumour of the of canal
• Congenital atresia

Middle ear

Common

• Acute otitis media
• Serous otitis media
• Tympanic membrane perforation

Uncommon

• Cholesteatoma
• Otosclerois
• Middle ear tumour
• Temporal bone trauma

Differentiating conductive and sensorineuronal hearing loss

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When a Weber test is carried out, sound localizes to the ear affected by the conductive loss. A Rinne test, in which air conduction is normally greater than bone conduction, is usually negative (abnormal), and shows higher greater bone conduction than air conduction.

Table 1. A table comparing sensorineural hearing loss to conductive

Criteria	Sensorineural hearing loss	Conductive hearing loss
Anatomical Site	Inner ear, cranial nerve VIII, or central processing centers	Middle ear (ossicular chain), tympanic membrane, or external ear
Weber Test	Sound localizes to normal ear	Sound localizes to affected ear (ear with conductive loss)
Rinne Test	Positive Rinne; Air conduction > Bone conduction (both air and bone conduction are decreased equally, but the difference between them is unchanged).	Negative Rinne; Bone Conduction > Air Conduction (Bone/Air Gap)

deaf culture | Otolaryngology