Hearing Loss in Adults and Children
- How Does Hearing Work?
The outer ear collects sound waves and works like a funnel to send them through a narrow tube (ear canal) that leads inside the ear. At the end of the ear canal is the eardrum (tympanic membrane). The tympanic membrane is a thin membrane that vibrates when sound waves strike it. It divides the area called the outer ear from the middle ear. It is attached to a set of three tiny bones in the middle ear. These bones are called the hammer (malleus), anvil (incus), and the stirrup (stapes). The bones pass the vibrations of sound waves to a small organ in the hearing part of the inner ear called the cochlea, which is a coiled structure like a snail shell. The inner ear is filled with a thin fluid that transmits pressure changes throughout the cochlea. Inside the cochlea are tiny hair cells that pick up sound vibrations from the fluid and cause nerve impulses in the auditory nerve. The auditory nerve carries the message to the brain, where it is interpreted as sound.
- Do I have a hearing loss?
Do you think you have a hearing loss? Often it is difficult to tell because hearing loss usually occurs gradually such that you might not be aware of it. Use the following indicators to see if you MAY have a hearing loss:
- Do family members complain about your inability to hear?
- Do you have difficulty understanding what people are saying in noisy places?
- Do you often ask people to repeat themselves?
- Do you find yourself avoiding social situations because you cannot hear?
- Do you turn up the volume on the TV so loud that others are complaining?
- Do you have difficulty determining which direction sounds are coming from?
- Do you have a history of exposure to loud noise (loud concerts, guns, construction, etc.)?
- Do you have difficulty hearing familiar sounds like the telephone and/or doorbell?
If you experience any or all of these problems on a consistent basis, you may have a hearing loss. You are not alone. 10% of the Canadian population suffer from some level of hearing loss; as many as half of these people are under the age of 65.
- What are the types of hearing loss?
Hearing loss typically produces a decrease in the detection and understanding of sound, particularly under challenging listening conditions such as background noise. The perception of both simple and complex sounds (e.g. speech and music) can be affected. Hearing loss may be associated with different types of health problems. There are two basic types of hearing loss:
Conductive Hearing Loss – occurs when sound cannot travel efficiently through the ear canal, ear drum or middle ear. Some of the primary, or common causes of conductive hearing loss include:
- Obstruction of the ear canal by ear wax or a foreign object
- Perforation or other damage to the ear drum
- Acute or chronic middle ear infections
- Injury/diseases affecting the small bones inside the middle ear
Conductive hearing loss is often reversible with medical or surgical treatment. If the hearing loss cannot be corrected then hearing aids are usually appropriate.
Sensorineural Hearing Loss – occurs when there is damage to the inner ear (cochlea) or auditory nervous system in the brain. Some of the common causes of sensorineural hearing loss are:
- Excessive exposure to loud noise
- Viral or bacterial infections
- Medications such as certain types ofantibiotics (gentamycin, streptomycin, erythromycin and vancomycin), ASA, and certain drugs given for the treatment of cancer (cisplatinum)
- Meniere’s Disease – an inner ear disorder which produces fluctuating hearing loss, periods/attacks of vertigo (dizziness), full feeling in the ears and tinnitus (ringing/buzzing in the ears)
- Gradual age-related hearing loss called presbycusis (affects 30% of persons over the age of 65)
- Acoustic Neuroma a tumor located between the ear and the brain and which usually affects balance as well as hearing.
Sensorineural hearing loss is a permanent type of hearing loss that usually can be helped with a hearing aid or other type of assistive listening device.
A Mixed Hearing Loss occurs when someone has a combination of a conductive and a sensorineural hearing loss.
- How do you know if hearing loss permanent or temporary?
With the exception of physical deformity, most conductive hearing losses can be treated medically or surgically. Conductive hearing losses can re-occur so monitoring is necessary. (Recurring middle ear fluid is particularly common in children.) Also, if left untreated, conductive hearing loss can become permanent. Treatment then becomes hearing aid amplification with assistive devices as necessary.
Sensorineural hearing losses cannot be corrected medically or surgically. When an individual is diagnosed with sensorineural hearing loss it is essential that they be fitted with hearing aid amplification as quickly as possible. Further, they will need to be seen by a Speech – Language Pathologist to assess language and communication needs. Assistive listening devices may also be necessary.
- What can I do about hearing loss?
If you suspect you have a hearing loss see a qualified audiologist to have your hearing evaluated. An audiologist is a health care professional trained to evaluate, diagnose, and provide rehabilitation for individuals with hearing loss. They have an advanced university education (Master’s or Doctorate) in Audiology.
Audiologists will provide the full range of tests necessary to determine the exact nature of your hearing loss and whether your condition warrants medical attention. No one is too young to have a hearing test, even a newborn. Audiologists are qualified to inform you about hearing aids . hey can select, fit and even dispense hearing aids and other assistive listening devices such as FM systems and infrared systems. As well they provide patient and family counseling about living with a hearing loss and hearing conservation programs to prevent hearing loss.
- How do I talk to someone with hearing loss?
People who have a hearing loss can feel very isolated and lonely. Listening becomes difficult and getting together with family and friends can become very frustrating. Here are some ways you can make communicating with someone with a hearing loss easier and more effective:
- Speak normally, not too exaggerated, too quickly or too loudly
- Be sure you have the persons attention before you begin speaking to them
- Look directly at the person to whom you are speaking so they can take advantage of speech reading (lip reading) cues
- Use facial expressions, gestures and body language to make it easier for the hard-of-hearing person to understand what you are saying
- Be aware of competing noises or sounds in the room such as music, other people talking, or mechanical sounds such as air conditioners. Background noises make it much more difficult to hear
- Reword your sentence if the hard-ofhearing person does not understand what you are saying
- Most importantly ask if there is anything you can do to improve communication
- What Causes Hearing Loss In Children?
Hearing loss present at birth is called congenital. It can be caused by:
- illness or infection the mother had during pregnancy
- medicines taken by the mother during pregnancy
- associated with other medical problems (syndromes)
- physical abnormality of any part of the ear
- hereditary factors
Hearing loss which develops later is called acquired. It can be caused by:
- difficulty during the birth
- meningitis, scarlet fever, mumps or other illnesses associated with high fever
- neurodegenerative disorders
- medications which are toxic to the inner ear
- head injury or trauma to the ear
- repeated or constant ear infections
- Should children protect their hearing?
22Tweens are at an age when they begin to act more independently. Now is a great time to teach them about protecting their hearing from noise-induced hearing loss (NIHL). Children, just like adults, are at risk for NIHL. This type of hearing loss occurs when tiny sensory hair cells in the inner ear are damaged by noises that are too loud and that last for too long. NIHL can be permanent. The ability to hear well helps children succeed in school, in sports and other activities, and in their personal relationships. Many sources of noise that can potentially damage the hearing of children are part of their daily, normal lives. Some potential sources of damaging noise include:
- Workshop tools and yard equipment
- Concerts of all music types
- Sporting events, hunting, and other leisure-time activities
- Trains, planes, all-terrain vehicles, tractors, and other vehicles
- School cafeterias and food courts
Most young people, however, are not aware of NIHL or how they can prevent it. In a survey conducted by the MTV Web site, only 16 percent of teens and young adults who responded reported that they had heard, read, or seen any information on NIHL (Pediatrics, 2005). Even when young people understand the risk of NIHL, they do not always follow through by adopting habits that protect their hearing. These habits are simple, such as turning down the volume on entertainment systems (e.g., MP3 players) or wearing earplugs or earmuffs in noisy environments. One study of college students found that even among those who knew about NIHL, almost three-quarters had never worn hearing protectors (Journal of the National Medical Association, 2004). These examples show why it is important to teach children about the causes and prevention of NIHL early on, so that healthy hearing habits become a natural choice. Tweens are at an age when they are developing as individuals and beginning to make some of their own choices. They are asking for a greater say in their after-school activities, music, and clothes. They also are developing their own health-related attitudes and habits, which can help or hurt their health for a lifetime. This age is a perfect opportunity to encourage tweens to adopt healthy hearing habits before and during the time that they develop their own listening, leisure, and working habits.
- Levels of Hearing Loss in Children
An audiologist plots a child’s responses to sounds on a graph called an audiogram. Test sounds vary in pitch from low to high pitch, measured by frequency in cycles per second. These sounds also vary in loudness (measured in decibels – dB). How loud a sound must be in order to be just barely heard represents the degree of hearing loss.
0 – 15 dB: Normal Hearing
Responses within this range suggest that a child has normal hearing ability. When understanding their ability to hear/understand speech it is important to consider their listening environment. A child with normal hearing ability can still have difficulty understanding in background noise at home or in school. Because a child is still learning language they need better hearing and a quieter environment than an adult to understand speech.
16 – 25 dB: Minimal Hearing Loss
- has difficulty with quiet or distant speech
- can miss up to 10% of the speech signal when the speaker is more than 3 feet away or there is background noise
- unaware of subtle conversation cues
- tires in listening situations and becomes restless
- has implications for learning language and following verbal instruction in the classroom can be conductive or sensorineural (temporary or permanent)
- may require hearing aid amplification
- may require special classroom amplification and instruction
26 – 40 dB: Mild Hearing Loss
- may miss 25-40% of the speech signal
- depends on visual cues to understand speech in background noisev
- appears very inattentive, “daydreams”
- becomes very tired in situations where just listening is involved
- needs hearing aid amplification and classroom amplification
- needs referral for follow up with a speech language pathologist
41 – 55 dB: Moderate Hearing Loss
- misses 50-100% of the speech signal, depending on the listening situation
- requires visual cues in conversation
- will have delayed language, limited vocabulary and imperfect speech
- communication is significantly affected and socialization becomes an issue
- requires hearing aid amplification and classroom amplification
- special education / resource may be required depending on when the loss is identified and treated
- speech – language pathology services needed
56-70 dB: Moderate Severe Hearing Loss
- normal conversation must be on a one – to – one basis, with no background distractions
- visual cues essential during communication
- child will have delayed language, poor speech intelligibility and atonal voice quality
- requires hearing aid amplification and classroom amplification
- resource help in the mainstream classroom
- speech – language pathologist to follow
71 – 90 dB: Severe Hearing Loss
- with proper amplification, should be able to identify environmental sounds and detect sounds of speech
- speech and language will be significantly delayed
- may choose a Total Communication approach to language and prefer the company of other children with hearing loss
- requires hearing aid amplification
- may need placement in a class for the hard-of-hearing, for some subjects
- may benefit from personal FM system
91 dB – > : Profound Hearing Loss
- more aware of vibrations than tonal patterns
- rely heavily on visual information for learning and communication
- adopt Total Communication or Sign Language
- education in program for the deaf to emphasize language skills and academics
- amplification choices include hearing aids, personal FM systems, vibrotactile hearing aids and cochlear implants
Unilateral hearing loss One normal hearing ear and the other ear with hearing loss:
- difficulty with faint of distant speech
- difficulty localizing sound and voices
- difficulty in background noise
- difficulty detecting speech from the ‘bad’ ear, especially in group discussion
- often treated as though they have ‘selective’ hearing
- tire in noisy listening situations, may appear inattentive or frustrated
- may benefit from personal or classroom FM system
- in quiet settings, a CROS hearing aid may be of benefit
- need favourable seating and lighting
- educational services as the needs arise
- How do I know if My Child Can Hear Me?
By watching your child’s responses to your voice and the sounds in his environment, and monitoring speech-language development you can get a good idea of how well your child can hear you. Here are some hearing milestones to consider:
0 – 3 Months
- recognize your voice and quiet down when spoken to
- stir or awaken when sleeping quietly and someone talks or there is a sudden noise
- respond to sound by starting, blinking, crying, quieting, or with a change in breathing
4 – 6 Months
- recognize familiar voices and quiet when spoken to
- babble for attention and use vocal play
- move eyes toward voices and interesting sounds
- notices musical toys or toys that make noise
- stir or awaken when sleeping quietly and someone talks or there is a sudden noise
7 – 12 Months
- enjoy musical or noise-making toys
- understand “no” and “bye-bye”
- imitate speech sounds
- directly turn to a sound nearby
- babbles using long and short groups of sounds (“baba”)
- add gesture to her communication
12 – 18 Months
- enjoys simple songs and rhymes
- points to pictures when named in books
- follow simple directions (e.g., ”go get your coat”)
- puts two words together
18 – 24 Months
- use 2-3 word sentences
- follow simple instructions (e.g.”go get your book”)
- use her own name
- use 150 – 300 words
- point to body parts when asked
By 24 Months
- have a vocabulary of 200-300 words, used in simple sentences
- have speech that is understandable to adults not in daily contact with your child
- be able to sit and listen to story books
Over 24 Months
- have speech that is understandable to adults not in daily contact with your child
- be alert to environmental sounds
- respond to someone talking out-of-view (particularly when there are no distractions)
- respond to voices on the telephone
- show consistent growth in vocabulary and use words to communicate
There are many things you can do to monitor and encourage your child’s speech-language development:
- Talk to your baby. It is important to talk to your baby through all your daily activities such as dressing, bathing, feeding, and playing.
- Use your baby’s name and be consistent with the name you use.
- Respond to the sounds your child makes.
- Sing to your baby as you play or snuggle for quiet time.
- Talk to your baby during daily activities and name the objects she contacts.
- Read colourful books together and talk about the pictures.
- Sing songs and nursery rhymes.
- Make fun sounds to see if she will imitate you.
- Listen to your baby. Make eye contact and respond to the sounds she makes.
- Play games with your baby such as “pat-a-cake” and “peek-a-boo”.
As your child gets older speak simply and clearly during daily activities about what you are doing. Listen and respond to your child’s speech. Read to your child daily. If your older child shows any of the following signs, he may be experiencing a hearing loss:
- intently watches the face of the person speaking
- uses “what?” or “huh?” frequently
- has difficulty understanding speech in group activities
- has difficulty hearing the television, radio, or music when others find it a comfortable loudness
A very important indication of hearing loss is the lack of or a delayed development of speech-language. If you have any concerns about your child’s responses to sound or speech-language development you should discuss your concerns with your family doctor and request an assessment with an audiologist and/or a speech-language pathologist.
- When Should A Child Be Referred For A Hearing Test?
Hopefully your child was born at a hospital that had newborn hearing screening available and testing would be done as a routine check in the newborn period. If not, or if you have concerns about your child’s responses to sound, these are some conditions that suggest a child might be at risk for hearing loss:
- family history of hearing loss in childhood
- maternal infections during pregnancy
- breathing difficulty at birth
- visible malformations of the head, neck or ears
- very low birth weight (less than 1500 grams)
- medications which cause hearing loss
- other medical conditions associated with hearing loss
- stay in a special care nursery for longer than 3 days
- prolonged mechanical ventilation lasting longer than 5 days
If your child comes under one of these categories, they should have their hearing tested before one month of age. When there is concern about potential hearing loss, ideally hearing testing should start within the first month of birth, with diagnosis confirmed by three months to facilitate early intervention by 6 months of age.
For older children, a referral should be made for a hearing test as soon as one of the following conditions arises:
- parental/caregiver/teacher concern regarding hearing, speech-language and/or developmental delay
- following meningitis, scarlet fever, mumps or other illnesses associated with high fever
- head injury with loss of consciousness or skull fracture
- diagnosis of a medical condition associated with hearing loss or neurodegenerative disorder
- exposure to medication toxic to the middle ear
- repeated or constant ear infections
- trauma to the ear
- How Do You Test Hearing In Young Children?
Depending on the age of the child and the concerns expressed, a number of tests are available. No child is too young to test.
Otoacoustic Emissions (OAE):
A small probe is placed in the child’s outer ear and a quiet clicking sound is presented. When the inner is stimulated a sound can be measured coming from the inner ear (cochlea). When this sound is recorded we know the cochlea is functioning and the child’s hearing will be roughly within normal limits. If this sound cannot be recorded the cause of the loss has not been determined. Further testing or re-testing at a later time will be necessary to determine if the loss is temporary (conductive) or permanent (sensorineural). This test is of benefit for children who are too young or too ill to give reliable responses to sound, yet determination of hearing ability is necessary. It is a very quick and harmless test which is frequently used in hearing screening programs for the earliest detection of hearing loss.
Auditory Brainstem Response (ABR):
Small (non-invasive) electrodes are placed on the child’s head to monitor ongoing electrical activity from the child’s scalp. A quiet clicking sound is introduced through earphones (which may either cover the ear or be placed in the ear canal). A computer then analyzes the changes in electrical activity to determine if the sound has been detected at a level loud enough to cause a change in electrical activity. Through this process, different pitches can be tested at different loudness levels to help determine level of hearing and type of loss. This test is also of benefit for those children too young to respond to routine testing. An automated version of this test is useful for newborn hearing screening programs.
This is the most common form of testing children. Age, physical abilities and developmental levels will determine which test procedures are used.
Behavioral Observation Audiometry (BOA):
Generally this is used with very young children, < 6 months, or children with limited physical movement. The child is seated in a sound-treated room. They are presented with sounds of varying pitch and loudness. The audiologist watches the child for obvious changes in behavior to indicate that they have heard the sound. Expected responses can be as subtle as an eye widening or as obvious as a startle or localization to the source.
Visual Reinforcement Audiometry (VRA) or Conditioned Orientation Response (COR):
Generally used with children 6-30 months of age. The child is seated in a sound-treated room and presented with sound of varying pitch and loudness. The expected response is localization to the sound source. When the child responds they are reinforced with a visual distracter.
Generally used with children 2 1/2 – 4 years or age. At this age the child is able to make a game of listening. When they hear a sound they are able to pair the sound with an activity in a game; i.e., fill a bucket with blocks, build a tower with stacking blocks, etc. Again the sound varies in pitch and loudness to determine the child’s ability to hear. At 4-5 years of age a child is generally able to be tested in the same manner as an adult. That is, they are presented with sounds of varying pitch and loudness and respond by either raising their hand or pressing a button to indicate when the sound is heard. For all of these behavioral tests, the child can be tested wearing earphones or through speakers in a sound-treated room. The use of earphones is preferred because you are better able to measure the hearing in both ears separately and test to a lower level.
Generally, immittance audiometry is used with other testing procedures to determine or confirm the presence of outer or middle ear problems. A small probe is placed snugly in the child’s ear and a slight pressure is introduced. As the pressure is changed in the ear canal we are able to monitor changes in the movement of the eardrum. Through this we are able to determine if the ear canal is clear, if the middle ear is clear, if the eardrum is whole, and if the middle ear bones are moving normally. This is an important test to identify conductive hearing loss. It is frequently used to monitor middle ear status for children with recurring middle ear fluid or to test if pressure-equalizing tubes are functioning. It does not test hearing sensitivity.
- What Are Some Amplification and Implant Options for Children?
If you suspect your child has a hearing loss see an audiologist. Your audiologist will determine the best course of action to help improve your child’s hearing. If amplification is a possible treatment for your child the following are some of the options available to you.
Behind-the-Ear Hearing Aid
This is the most popular style of hearing aids for children because it provides the greatest amount of flexibility for the fitting. This type of hearing aid sits behind your child’s ear and simplified sound is routed to the ear through an ear mold. BTE hearing aids are good for children who are still growing as the ear mould can be changed as they grow without changing the hearing aid itself. This style of hearing aid can provide the amplification necessary for all degrees of hearing loss from mild to profound. BTE hearing aids can be used with a variety of other assistive devices including FM systems, telephone adaptors, television amplifiers and many others. Because the electronics are behind the ear, BTEs are particularly useful for those with chronic ear infections, excess cerumen (ear wax) and those with small ear canals. Behind-the-ear hearing aids and ear moulds come in a variety of colours and designs.
In-the-Ear Hearing Aid
This type of hearing aid fits in the ear canal and the concha (outer portion of the ear). This is a very popular style for adult hearing aid users but there are drawbacks for use with children who are still growing and active. They cannot be used with many assistive listening devices including direct audio input FM systems. Also, your child’s ears are continually growing which results in the need for frequent re-casing and re-shelling of the hearing aids. While this is being done, your child is usually left without amplification for a few days. This style of hearing aid cannot provide adequate amplification for individuals with severe to profound hearing losses.
CROS (Contralateral Routing of Signal)
This hearing system is designed for people with one ear that is unaidable (i.e. insufficient hearing to benefit from traditional hearing amplification). The better ear can have normal hearing (CROS Aid) or have some hearing loss as well (Bi-CROS). A microphone is placed on the poorer ear and the sound from that microphone is routed to a hearing aid on the better ear. This provides sound from the side of the head that has unaidable hearing . While this does not restore full ability to localize sounds in space, it does provide useful sound information that is not otherwise available to the individual.
These are assistive listening devices used to improve the signal-to-noise ratio for the listener and to reduce the effects of poor acoustics. This system is made up of two parts:
- the transmitter which is used by the speaker or placed near or connected to the device to be amplified (eg.TV, computer, stereo); and
- the receiver which is used by the listener.
A personal FM system helps to bring the speaker’s voice directly to the listener’s ears either through hearing aids or headphones. The listener is able to hear the speaker above the background noise at considerable distances. There are no wires connecting the listener to the speaker which gives mobility to both. These units are sometimes used with infants and young children but are essential to the child with hearing loss in the classroom.
Sound field FM systems provide amplification for the whole classroom through the use of loudspeakers while the teacher wears a transmitter. This system has direct benefits to every child in the classroom but is particularly helpful for:
- children with history of middle ear infection
- children with unilateral hearing loss
- children with minimal hearing loss who do not wear hearing aids
- children with mild-to-moderate hearing loss who do wear hearing aids
- children with normal hearing who have central auditory processing problems or attention difficulties
- children in early primary grades with normal hearing who are in the critical stages of developing academic competencies
These systems provide benefit to teachers as well because there are fewer incidents of vocal fatigue among users.
A device surgically implanted into the cochlea to bypass the sensory organ to activate the hearing nerve directly. It is designed for individuals with severe-profound sensorineural hearing loss who do not benefit from hearing aid amplification. The system consists of a microphone, a cable, transmitter and speech processor which fit behind the ear, and the internal portion of the device (the magnet and receiver/stimulator) which are implanted in the mastoid process (behind the pinna). Once implanted, the device is programmed for the individual child over several months.
The criteria for candidacy for cochlear implants is routinely updated and varies among Canadian cochlear implant centres. Please check with your local cochlear implant professional for the latest criteria.
BAHA (Bone Anchored Hearing Aid)
This device combines a sound processor with a small titanium fixture implanted behind the ear within the skull or held on the skull with a soft headband. The non-surgical option on a headband is suitable for younger children who do not meet the age criteria for the surgical option. The system allows sound to be conducted through the bone rather than via the middle ear – a process known as direct bone conduction. Children with chronic ear infections, and malformed outer ears are candidates for this type of device.