What is Hearing Impairment? - Definition, Causes & Treatment

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  • 0:01 Understanding Hearing…
  • 1:38 Types And Causes of…
  • 4:28 Treatment
  • 6:08 Lesson Summary
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Lesson Transcript
Instructor: Yolanda Williams

Yolanda has taught college Psychology and Ethics, and has a doctorate of philosophy in counselor education and supervision.

This video lesson discusses hearing impairment, from the different types and their causes to available treatment options. Following the lesson is a short quiz to test your knowledge.

Understanding Hearing Impairment

You already know that hearing is one of the five senses that allows us to perceive sound. Hearing impairment, or hearing loss, occurs when you lose part or all of your ability to hear. Other terms that are used to refer to hearing impairment are deaf and hard of hearing.

Hearing impairments are classified in terms of the severity and type of hearing impairment. The severity of the hearing impairment is categorized based on the minimum sound that can be heard with your better ear. The higher the decibel (dB), the louder the sound.

With mild hearing impairment, the minimum sound that can be heard is between 25 and 40 dB. People at this level cannot hear soft noises and may have trouble following conversations in noisy settings.

With moderate hearing impairment, the minimum sound that can be heard is between 40 and 70 dB. People at this level cannot hear soft or moderately loud noises and may have trouble hearing unless they use a hearing aid.

With severe hearing impairment, the minimum sound that can be heard is between 70 and 95 dB. People at this level are unable to hear most noises and may rely on lip-reading and/or sign language, even with the use of a hearing aid.

With profound hearing impairment, the minimum sound heard is 95 dB and over. People at this level may only hear very loud noises and rely solely on lip-reading and/or sign language. Hearing aids are not effective.

Now, let's take a look at the types and causes of hearing impairment.

Types and Causes of Hearing Impairment

Conductive hearing loss is when a hearing impairment is due to problems in the outer ear, middle ear, ear canal, eardrum, or the ossicles, which are the tiny bones in the middle ear. When the sound is not being conducted properly through the ear, conductive hearing loss occurs. Most cases of conductive hearing loss can be corrected medically or surgically.

Causes of conductive hearing loss include:

  • Fluid in the middle ear as a result of colds
  • Otitis media, commonly referred to as ear infection
  • Poor eustachian tube function
  • Perforated eardrum
  • External otitis, commonly referred to as ear canal infection
  • Allergies
  • Earwax buildup
  • Benign tumors or having a foreign body in the ear
  • Structural abnormalities of the outer ear, ear canal, or middle ear

Sensorineural hearing loss (SNHL), also referred to as nerve hearing loss, occurs when there is damage to either the auditory nerve or the cochlea, which is the inner ear. The hearing loss in SNHL is permanent, although it may be possible to treat it with hearing aids.

Causes of SNHL include:

  • Exposure to excessively loud noise
  • Head trauma or sudden air pressure changes (e.g., during airplane descent)
  • Illnesses, such as Meniere's disease and meningitis
  • Structural abnormality of the inner ear
  • Tumors
  • Aging
  • Medication side effects (e.g., aspirin and Vicodin)
  • Autoimmune inner ear disease
  • Otosclerosis, the abnormal growth of the bone that is in the middle ear

When conductive hearing loss and SNHL occur at the same time, it is referred to as mixed hearing loss. Mixed hearing loss occurs when there is both damage to the outer or middle ear and damage to the inner ear.

Central hearing loss occurs when there are problems within the brain that interfere with the ability to interpret or understand sounds. This is the rarest type of hearing impairment and the hardest to treat.

Causes of central hearing loss include:

  • Damage to brainstem structures
  • Severe head trauma
  • Damage to the auditory nerves or the pathways that lead to them
  • Brain tumors

Functional hearing loss occurs when the functioning of the ears is normal, but the person is showing a reduced response or not responding at all to sounds. Because there are no functional hearing problems in individuals with functional hearing loss, it is the most difficult type of hearing loss to detect and the most often misdiagnosed. Functional hearing loss is caused by mental health problems, such as ADHD and depression.


Treatment depends on several factors, including:

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