Normal
0–20 dB
Mild
21–40 dB
Moderate
41–55 dB
Moderately severe
56–70 dB
Severe
71–90 dB
Profound
>90 dB
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Mild to moderate range. Most individuals who experience reduced hearing in the mild and moderate ranges are able to access sufficient auditory information so that their hearing does not significantly impact their ability to develop linguistic competence or to perform academically. Yet, even a mild hearing loss can make it difficult for individuals to attend, to alert to their surroundings, and to appreciate what is happening around them. A mild to moderate hearing loss can influence one’s communication abilities and impact social relationships.
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Severe and profound range. Hearing status in the severe and profound ranges often limits access to spoken language and influences educational and communication options. Individuals with hearing in this range may communicate using a visual language (e.g., American Sign Language (ASL) as used in the USA and Canada or another formal signed language used elsewhere in the world). Alternatively, a person may have varying degrees of ability to use spoken language with the aid of hearing aids or cochlear implants.
Cause of hearing loss
Conductive hearing loss | Disruption of sound waves caused by a physical blockage, typically in the middle ear, that limits hearing. Most frequently, conductive hearing loss is temporary and can be caused by otitis media (ear infections), “fluid in the ears” as a result of a sinus infection, or excessive cerumen (earwax). In such cases, removal of the blockage can restore hearing. Anatomical anomalies can also result in conductive hearing loss, which may be more permanent |
Sensorineural hearing loss | Structural alterations to the nerves in the inner ear, most commonly in the hair cells of the cochlea or the auditory nerve (i.e., VIII cranial nerve) resulting in reduced hearing. Sensorineural hearing loss is permanent and can be progressive (i.e., it can worsen over time). The majority of individuals who are considered deaf or hard of hearing have this type of hearing loss |
Mixed hearing loss | Hearing loss that has both conductive (blockage) and sensorineural (nervous system) components is referred to as a mixed hearing loss |
Auditory neuropathy/auditory dyssynchrony | This type of hearing loss, often referred to as “AN,” is a result of improper transmission of sound from the inner ear to the auditory nerve or to the brainstem. This type of hearing loss often results in inconsistent hearing abilities, with periods of normal or near-normal hearing and periods of significant loss, making access to sound highly unpredictable |
Time of onset
The timing of the onset of reduced hearing has significant implications for the individual’s functioning and life experience. Typically, onset is characterized as congenital, prelingual, or postlingual, referring to whether the reduced hearing is present at birth, before a child has developed spoken language or after spoken language has been established. Congenital and prelingually acquired hearing loss may interfere with an individual’s ability to develop spoken language abilities. Hearing loss that is acquired postlingually is less likely to have as significant of an impact of the development of spoken language skills. Once a child has developed a solid foundation in spoken language, experiencing a reduction in hearing abilities will not necessarily inhibit further development of speech and language.
Benefit from assistive devices [ 2 ]:
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Hearing aids. Many individuals with mild and moderate levels of hearing are able to access auditory information with the use of hearing aids. Typically, these amplify sound, but do not necessarily clarify the sounds that are heard. For many people, hearing aids allow for some, but not perfect, understanding of what is happening in their environment and can reduce the social isolation that can accompany progressive hearing loss.
- b.
Cochlear implants. Individuals with more profound levels of reduced hearing may qualify for a cochlear implant. This is a device with electrodes that are inserted directly into the cochlea that sends an electrical impulse to the auditory nerve. In the USA, candidacy for cochlear implant surgery is largely determined by the Federal Drug Administration (FDA). New technologies, such as hybrid cochlear implants, which function as a cochlear implant in the frequency ranges in which a person has a profound hearing loss and function as a hearing aid in the ranges in which a person hears better, helping to preserve some “natural hearing,” are now available.
- c.
Hearing assistive technologies (HAT). Many deaf and hard of hearing individuals benefit from additional supports to promote their auditory access. Personalized listening frequency modulation (FM) systems are like individualized radio stations that operate on special frequencies. For example, personal FM systems can be used to target a speaker’s voice directly to the microphones of an individual’s hearing aids. Small, wireless, personalized microphones are another example of technology for amplification. These look similar to a writing pen and can be used discretely to improve hearing in loud environments or over a distance (such as across a large room). In group settings, these “smart devices” can detect the direction from which speech is coming and enhance the listener’s access to that sound, over the background noises in the room.
- d.
Visual technologies. For individuals who cannot hear certain environmental sounds, visual supports can be employed to ensure they are aware of their surroundings. Doorbells can be connected to a lamp, for example, which will flicker when a guest has arrived; fire alarms can be linked with flashing lights, and alarm clocks can be attached to vibrating devices that can wake a person who is deaf or hard of hearing from a deep sleep.
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Terminology
The terms used to describe and understand individuals with reduced hearing vary depending on the context of the hearing status. Individuals with reduced hearing sensitivity are typically referred to as hard of hearing, deaf, or Deaf [3]:
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Hearing loss
The phrase “individuals with hearing loss” has been commonly used, yet increasingly this has changed to “individuals with reduced hearing” to reflect the understanding that not all individuals with limited auditory access have experienced a “loss” of hearing (e.g., when an infant is born with reduced hearing, she may not have ever had a full range of hearing).
- 2.
Hard of hearing
Typically, an individual who identifies as hard of hearing has some degree of reduced hearing yet can still access sound and spoken language. Audiologically , this term often refers to a person whose hearing loss is in the mild or moderate range.
- 3.
deaf
When the hearing status is further reduced, and a person’s auditory input is minimal such that there is limited functional access to spoken language, the term deaf may be used. From an audiological perspective, the person may have reduced hearing sensitivity in the severe to profound or profound range.
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Deaf
When an individual has significantly reduced hearing sensitivity, he may identify as Deaf and belong to the Deaf community, a recognized linguistic and cultural group. For those who self-identify as members of the Deaf community, the use of a uniform signed language and the incorporation of Deaf cultural norms are common. For “capital D (Deaf)” individuals, reduced hearing sensitivity is not perceived as a loss but rather as Deaf gain, the recognition by members of the Deaf community that being Deaf has added numerous benefits to their lives.
- 5.
Hearing impairment
This a term that has historically been applied to individuals with reduced hearing. However, this term is not accepted by members of the Deaf community and is perceived as disrespectful.
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Importance
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Incidence and prevalence :
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At birth
The incidence of children born with profound hearing loss is 1 in 1000 births; the number of children born with reduced hearing sensitivity of any degree is 3 in 1000 [4].
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Children 12 years of age and younger
Recurrent otitis media (ear infection) is the leading cause of mild hearing loss for children. One in eight children under the age of 12 experiences some degree of hearing loss [5].
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Adults over the age of 18
A study conducted in the USA revealed that, in adults over age 18, 15 % experience reduced hearing [6]. The prevalence of reduced hearing increases substantially in older members of the population.
- 4.
Adults 70 years plus
Nearly two-third of adults age 70 and older experience significant hearing loss that impacts their functioning, particularly in the social realm [5].
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