The different types of hearing loss : 

A. Conductive hearing loss

Affected : outer and/or middle ear.
Mechanism : sound is not transmitted correctly to the cochlea.

Common causes :

  • Earwax blockage, foreign body
  • Otitis externa or otitis media
  • Perforated eardrum
  • Otosclerosis
  • Malformation of the outer ear, ear canal, or ossicles

Audiometric characteristics :

  • Parallel slope curve, loss in the air conduction pathway with normal bone conduction
  • Significant transmission gap

           Treatment :

      • Medical (removal of wax plug, treatment of otitis)
      • Surgical (tympanoplasty, stapedectomy)
      • Apparatus if residual hearing loss : air conduction or bone conduction hearing aids

B. Sensorineural hearing loss

Affected : inner ear (cochlea) and/or auditory nerve.
Mechanism : damage to hair cells or auditory nerve pathways.

Common causes :

  • Presbycusis (age-related hearing loss)
  • Prolonged exposure to noise
  • Acoustic trauma or barotrauma
  • Ototoxic medications (aminoglycosides, cisplatin, etc.)
  • Viral, autoimmune, or genetic disorders

Audiometric characteristics :

  • Overlapping air and bone conduction curves
  • Often sloping downward (high-frequency hearing loss)

         Treatment :

      • No curative medical treatment in most cases
      • Rehabilitation with digital hearing aids or cochlear implants depending on severity

C. Mixed hearing loss

Affected : both transmission and perception.
Audiogram : loss on both curves, with partial air-bone gap.

Causes :

  • Advanced otosclerosis
  • Chronic otitis with cochleovestibular involvement
  • Trauma

         Treatment :

      • Treatment of the underlying cause, if possible
      • Appropriate hearing aids (high gain, wide bandwidth)

D. Central hearing loss

Affected : central auditory pathways (brain stem, cortex).
Mechanism : sound is perceived but misinterpreted.

Possible causes :

  • Neurological damage (stroke, tumor, head injury)
  • Central auditory processing disorder (CAPD)

Special feature :

  • Audiogram sometimes normal
  • Disproportionate comprehension difficulties

           Treatment :

      • Speech therapy rehabilitation
      • Listening strategies and communication accommodations