Hearing Loss & Deafness

Because hearing is so critical to communication skills and development, hearing loss can have a significant impact on speech and language skills. Hearing loss is described according to type, degree and configuration.

Type of Hearing Loss:

There are 3 types of hearing loss that refer to which part of the auditory system is affected:

A conductive hearing loss occurs when there is obstruction or pathology to the outer or middle ear, resulting in a reduction in sound level. Conductive hearing loss may be caused by:

• Middle ear fluid
• Outer or middle ear infection
• Impacted earwax
• Perforated eardrum
• Presence of a foreign body

A conductive hearing loss can often be medically or surgically treated. Hearing aids may help amplify sound levels.

A sensorineural hearing loss occurs when there is damage to the inner ear organ of hearing, the cochlea, or to the auditory nerve pathway from the cochlea to the brain. Sensorineural hearing loss results in both a reduction in sound level and the ability to understand and clearly hear speech. Sensorineural hearing loss may be caused by:

• Disease, such as Meningitis or Measles
• Ototoxic drugs
• Genetic syndromes
• Noise exposure
• Aging
• Tumors

Sensorineural loss is permanent and cannot be corrected medically or surgically.

A mixed hearing loss is a combination of conductive and sensorineural hearing loss. In this case, both the outer or middle ear and the inner ear are affected.

Degree of Hearing Loss:

Degree of hearing loss refers to the amount or quantity of the loss. Normal thresholds of hearing sensitivity are between 0 and 20 dB. Average speech signal level is between 50 and 60 dB.

Thresholds between 20 and 40 dB indicate a mild loss.
Thresholds between 40 and 60 dB indicate a moderate loss.
Thresholds between 60 and 80 dB indicate a severe loss.
Thresholds above 80 dB indicate a profound loss.

Configuration of Hearing Loss:

Configuration of hearing loss classifies hearing loss according to which frequencies are affected.

A high-frequency hearing loss would indicate good hearing sensitivity for lower frequencies and poorer hearing sensitivity for higher frequencies.
A low-frequency hearing loss would indicate good hearing sensitivity for higher frequencies and poorer hearing sensitivity for lower frequencies.
A flat configuration would indicate no difference between hearing sensitivity for low and high frequencies.