Conductive, Sensorineural and Mixed Hearing Loss

Types of Hearing Loss

Hearing loss can be categorized by which part of the auditory system is damaged. There are three basic types of hearing loss: conductive hearing loss, sensorineural hearing loss, and mixed hearing loss.

Conductive Hearing Loss

Conductive hearing loss occurs when sound is not conducted efficiently through the outer ear canal to the eardrum and the tiny bones (ossicles) of the middle ear. Conductive hearing loss usually involves a reduction in sound level or the ability to hear faint sounds. This type of hearing loss can often be corrected medically or surgically. Some possible causes of conductive hearing loss:

  • Fluid in the middle ear from colds
  • Ear infection (otitis media)
  • Allergies (serous otitis media)
  • Poor eustachian tube function
  • Perforated eardrum
  • Benign tumors
  • Impacted earwax (cerumen)
  • Infection in the ear canal (external otitis)
  • Swimmer's Ear (otitis ecxterna)
  • Presence of a foreign body
  • Absence or malformation of the outer ear, ear canal, or middle ear

Sensorineural Hearing Loss

Sensorineural hearing loss (SNHL) is by far the most common hearing loss. The condition refers to problems in the cochlea or auditory nerve. Most are due to deterioration of the tiny hair cells that line the cochlea and transmit sound to the auditory nerve and then the brain. This accounts for 90% of permanent hearing loss. Sensorineural hearing loss can't be corrected medically, but can usually be improved through the use of hearing instruments. Some possible causes of SNHL:

  • Illnesses
  • Drugs that are toxic to hearing
  • Hearing loss that runs in the family (genetic or hereditary)
  • Aging
  • Head trauma
  • Malformation of the inner ear
  • Exposure to loud noise

Mixed Hearing Loss

Sometimes a conductive hearing loss occurs in combination with a sensorineural hearing loss (SNHL). In other words, there may be damage in the outer or middle ear and in the inner ear (cochlea) or auditory nerve. When this occurs, the hearing loss is referred to as a mixed hearing loss.