Hearing Loss - Beyond Early Childhood

See the Hearing Loss (Adults) and the Hearing Loss (School-Age) Evidence Maps for summaries of the available research on this topic.

Hearing loss is the result of impaired auditory sensitivity and/or diminished speech intelligibility of the physiological auditory system. Individuals with hearing loss are sometimes described as deaf or hard of hearing based on the type, degree, and configuration of hearing impairment.

There are three basic types of hearing loss: sensorineural, conductive, and mixed.

Sensorineural hearing loss (SNHL) is hearing loss due to cochlear (sensory) or VIIIth nerve (neural) auditory dysfunction. Most of the time, SNHL cannot be medically or surgically corrected. Presbycusis is a sensorineural hearing loss that occurs gradually, later in life, affecting hearing in both ears over time. The loss associated with presbycusis is usually greater for high-pitched sounds.

Conductive hearing loss occurs when there is a problem conducting sound waves easily through the outer ear canal, tympanic membrane, or middle ear (ossicles). Conductive hearing loss makes sounds softer and more difficult to hear. This type of hearing loss may be responsive to medical or surgical treatment.

Mixed hearing loss is the result of damage to conductive pathways of the outer and/or middle ear and to the nerves or sensory hair cells of the inner ear.

Degree of Hearing Loss

Degree of hearing loss refers to the severity of the loss. The table below shows one of the more commonly used classification systems.

Degree of hearing loss Hearing loss range (dB HL)
Normal –10 to 15
Slight 16 to 25
Mild 26 to 40
Moderate 41 to 55
Moderately severe 56 to 70
Severe 71 to 90
Profound 91+

Adapted from Clark, 1981.

The degree of hearing loss can have significant implications for children with hearing loss, as even a slight hearing loss can be educationally significant for children in the school setting.  Educationally significant hearing loss has been defined as "any hearing loss that potentially interferes with access to classroom instruction and impacts a child or youth's ability to communicate, learn and develop peer relationships (Johnson & Seaton, 2012, p. 43).

Configuration of Hearing Loss

The configuration, or shape, of the hearing loss refers to the degree and pattern of hearing loss across frequencies (tones), as illustrated in a graph called an audiogram. For example, a hearing loss that affects only the high tones would be described as a high-frequency loss. Its configuration would show good hearing in the low tones and poor hearing in the high tones. On the other hand, if only the low frequencies were affected, the configuration would show poorer hearing for low tones and better hearing for high tones. Some hearing loss configurations are flat, indicating the same amount of hearing loss for low and high tones.

In addition, hearing loss may be bilateral or unilateral, symmetrical (degree and configuration of hearing loss are the same in each ear) or asymmetrical, progressive or sudden in onset, and fluctuating or stable.

Frequency Figure

Note: The scope of this content is limited to the diagnosis and management of hearing loss for individuals ages 5 years and older from an audiological perspective. Resources for hearing screening and habilitation are under development. See the permanent childhood hearing loss page for information on hearing loss for children from infancy through age 5.

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