About Hearing Loss
Some facts about hearing loss:
- Approximately 36 million Americans suffer from hearing loss.
- More than half of the people with hearing loss are younger than age 65.
- Untreated hearing loss can affect your ability to understand speech and can negatively impact your social and emotional well-being—hearing impairment can decrease your quality of life!
- Hearing loss is the third most common health problem in the United States.
When describing hearing loss we generally look at three attributes: type of hearing loss, degree of hearing loss, and the configuration of the hearing loss.
Type of Hearing Loss
Hearing loss can be categorized by where or what 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, or ossicles, of the middle ear. Conductive hearing loss results in 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
Sensorineural hearing loss occurs when there is damage to the inner ear (cochlea) or to the nerve pathways from the inner ear (retrocochlear) 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 often 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
- genetic syndromes
- noise exposure
- viruses
- head trauma
- aging
- tumors.
Mixed Hearing Loss
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.
The type of hearing loss – conductive, sensorineural, or mixed – can be determined by comparing testing done with earphones and testing done with a special bone oscillator generally placed on the mastoid (the bone behind the ear).
Degree of Hearing Loss
Degree of hearing loss refers to the severity of the loss. During the hearing evaluation, patient responses to pure tone stimuli of different frequencies are plotted on a graph called an audiogram. The numbers are representative of the patient's thresholds, or the softest intensity, measured in decibels at which sound is perceived. The following chart provides an idea of the impact of different levels of hearing loss:
Degree of Hearing Loss |
Hearing Loss Range (in dBHL) |
Impact of Hearing Loss |
Normal |
0-25 |
Normal hearing, no significant difficulty |
Mild |
26-40 |
Difficulty hearing soft or distant speech, may notice more difficulty hearing in background noise. |
Moderate |
41-70 |
Difficulty hearing normal conversational speech, higher volume needed for TV/radio |
Severe |
71-90 |
Normal conversational speech is largely inaudible. You may also have difficulty with loud speech or only be able to understand shouted or amplified speech. |
Profound |
91+ |
Unable to understand even amplified speech; may be a candidate for a cochlear implant. |
Configuration of Hearing Loss
The configuration or shape of the hearing loss refers to the extent of hearing loss at each frequency and the overall picture of hearing that is created. For example, a hearing loss that only affects the high frequencies would be described as a high-frequency loss. Its configuration would show good hearing in the low frequencies and poor hearing in the high frequencies. On the other hand, if only the low frequencies are 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.
Hearing Loss in Children
Hearing is critical for the development of speech, language, communication skills and learning. Even a mild hearing loss in a child, can cause speech and language delays and have negative consequences on academic performance and cognitive development. Ear infections are also common in childhood and can cause decreased hearing. Parents are usually the best judge of their child’s hearing. If you do suspect a hearing problem, it is a good idea to have your child’s hearing evaluated sooner rather than later.
Infants who have failed the newborn hearing screen can be evaluated further and can be fit with amplification as early as a few weeks old should a permanent hearing loss be discovered. Children at this age are usually evaluated by auditory brainstem response (ABR) and by otoacoustic emission (OAE) testing. The Center for Audiology does not perform ABR testing at this time; however, we will refer you to the appropriate facility for that testing. The Center for Audiology is equipped to fit hearing aids even on infants. Once a child reaches approximately twelve months old, visual reinforcement audiometry is attempted, whereby a child is conditioned to turn toward the sound each time he/she hears it. At two and a half to three years of age, play audiometry is used. The child is conditioned to respond with a play response (throw a block into a bucket, place a peg on a board, etc.) each time he/she hears the sound. By five years of age, traditional (raise your hand) audiometry is used. Research indicates that children identified with hearing loss who begin services before 6 months old will develop language (spoken or signed) on par with their hearing peers.
To learn more about hearing loss and related topics, please visit the following links:
- Better Hearing Institute
- Dangerous Decibels
- How's Your Hearing?
- American Tinnitus Association
- Hearing Loss Association of America