Types and Degrees of Hearing Loss
Types of Hearing Loss
 Source: American Speech-Language-Hearing Association

Conductive- Conductive hearing loss occurs when sound is not conducted efficiently through the outer ear to the eardrum and the tiny bones of the 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 medically or surgically corrected.

Examples of conditions that may cause a conductive hearing loss include:
  • Conditions associated with middle ear pathology such as fluid in the middle ear from colds, allergies (serous otitis media), poor eustachian tube function, ear infection (otitis media), perforated eardrum, benign tumors
  • Impacted earwax (cerumen)
  • Infection in the ear canal (external otitis)
  • Presence of a foreign body
  • Absence or malformation of the outer ear, ear canal, or middle ear

Sensorineural hearing loss occurs when there is damage to the inner ear (cochlea) or to the nerve pathways from the inner ear to the brain. Sensorineural hearing loss cannot be medically or surgically corrected. It is a permanent loss.

Sensorineural hearing loss not only involves a reduction in sound level, or ability to hear faint sounds, but also affects speech understanding, or ability to hear clearly.

Sensorineural hearing loss can be caused by diseases, birth injury, drugs that are toxic to the auditory system, and genetic syndromes. Sensorineural hearing loss may also occur as a result of noise exposure, viruses, head trauma, aging, and tumors.

Mixed- Sometimes a conductive hearing loss occurs in combination with a sensorineural hearing loss. 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.

Unilateral- Unilateral hearing loss (UHL) means that hearing is normal in one ear but there is hearing loss in the other ear. The hearing loss can range from mild to very severe. Approximately one out of 1000 children is born with UHL. Unilateral hearing loss can occur in both adults and children. Nearly 3% of school-aged children have UHL. Children with UHL are at higher risk for having academic, speech/language and social/emotional difficulties than their normal hearing peers. Some children with UHL experience these difficulties but others do not.

Other Types of Hearing Loss

Auditory Processing Disorder-
This is when all of the parts of the ears function correctly but the brain cannot process the sound it receives.

Cortical Deafness- deafness caused by disease of the cortical centers of the cerebrum in the brain. Source- The American Heritage Medical Dictionary 2007. 

Degrees of Hearing Loss

Information adapted from Help Kids
db- decibels

Normal 0-15db No hearing loss and all sounds are heard.
Mild- 15-40db  Hears only some louder voiced speech sounds
Moderate- 40-65db Misses most speech at normal conversational level
Severe- 65-95db Hears no speech sounds of normal conversation
Profound- 95+db Hears no speech sounds or other sounds

Other Hearing Loss Terms

Bilateral- Hearing loss in both ears.
Unilateral- Hearing loss in one ear.
Progressive- A continued reduction in hearing.
Sudden- A hearing loss that starts suddenly.
Fluctuating- A hearing loss that is not stable. It may become better and worse over time.