A Parent's Guide Of Hearing (English Version)
Your child deserves a head start...
Checklist of Important Points about Hearing and Hearing Impairment: English Version
- Auditory stimulation is necessary for the development of critical auditory brain centres.
- Hearing and listening form the invisible cornerstones of the language/learning system.
- Hearing impairment occurs along a broad continuum ranging from a slight hearing loss to a profound hearing impairment.
- Hearing loss, whether slight or profound in nature, if unmanaged, has a negative impact on the development of spoken language communication, reading, writing, and academic competencies.
- Human beings are neurologically wired to develop spoken language and reading skills primarily through the central auditory system.
- Speech may be audible to someone with a hearing impairment but not necessarily intelligible enough to hear one word as distinct from another.
- Any type and degree of hearing problem can present a significant barrier to the child's ability to receive information from the environment.
- Children with hearing impairments need to be taught, directly, many concepts, vocabulary, and social/emotional cues that children with normal hearing learn incidentally.
- A minimal hearing loss can seriously affect the overall development of an infant or child who is in the process of learning language, developing spoken communication skills, and acquiring knowledge.
- Support groups are available to parents. Ask your Audiologist.
How your Child Hears
Some basic knowledge in the anatomy and function of the ear will help you better appreciate how your child hears. The ear can be divided into 3 parts:
The Outer Ear
The Outer Ear consists of the pinna and the ear canal. The pinna collects and funnels the sound waves into the ear canal. Because of its horn shape, the ear canal, amplifies the incoming sound waves or acoustical energy arriving at the eardrum.
The Middle Ear
The Middle Ear consists of the eardrum, the 3 tiny bones, also called ossicles (malleus, incus, and stapes), and the Eustachian tube. The sound waves set the eardrum into vibration which in turn set the 3 tiny little bones into motion. The ossicular chain magnifies the incoming sound waves which have now been converted into mechanical energy. Their movement sets up the oval window which is the entrance to the inner ear. The Eustachian tube supplies air to the middle ear cavity and equalizes air pressure on both sides of the eardrum.
The Inner Ear
The Inner Ear consists of the vestibular system and the cochlea. The vestibular system is the organ for balance, and the cochlea is the sensory organ of hearing. The cochlea, which is snail-shaped, is filled with fluid. Its main role is to convert the mechanical energy of the middle ear into neural energy. The cochlear fluids displace the thousands of hair cells which transform the hydraulic movement into electrical impulses. These electrical impulses stimulate the auditory nerve and are transmitted to the brain.
Causes of Hearing Loss
Hearing losses are generally classified as either being congenital or acquired.
Congenital hearing losses
(early-onset) refer to losses of hearing occurring before, at, or shortly after birth but prior to learning of speech and language, usually before the age of 3 years.
Acquired hearing losses
(later-onset) occur after speech and language develop, or after 3 years of age.
Some known causes of hearing loss include:
- Genetic with the most common being a mutation in the connexion 26 gene
- Associated with over 200 syndromes such as Waardenburg, Alport's, Crouzon, Treacher Collins
- Some anomalies such as ossicular abnormalities, atresia, microtia, stenotopic ear canal
- Viral infections such Toxoplasmosis (Cat-scratch disease); Syphilis; Rubella (German measles); Cytomegalovirus (CMV); and Herpes
- At risk factors such as Hyperbilirubinemia (jaundice); low birth weight 1500 grams (approx. 3.3 lbs.); low APGAR score, where A is Activity (muscle tone); P: Pulse; G: Grimace (reflex irritability); A: Appearance (skin color); and R: Respiration
- Ototoxicity, for example, certain drugs such as gentamycin, tobramycin, kanamycin, streptomycin that may be prescribed to treat serious infections or birth complications
- Illnesses, such as bacterial or viral meningitis, middle ear infections
Unfortunately, in some cases (25%), there are no known causes to explain why a child has a hearing loss.
Signs of Hearing Loss
- not startled by intense sounds
- does not understand someone that is out-of-view
- does not respond when called
- cannot seem to localize sound
- toddlers may want to turn up the volume of the television or radio when others find it a comfortable loudness
- needs things to be repeated or uses "what?" or "huh?" frequently
- does not respond to voices over the telephone
- stops early babbling
- does not say a single word by 12 months
- frequently gets ear infections (a child may tug at ears and/or show pain and fever)
- family history of hearing loss, malformation of the ears
In fact, any parental concern about your child's hearing justifies a visit to an Audiologist.
Milestones of Communication
There are several behaviours a child with normal hearing should display based on age and stage of development. Some of the milestones of communication (hearing, speech, and language) development that mark the progress of young children as they learn to communicate and gain speech and language skills are as follows:
BIRTH TO 3 MONTHS
- child awakens to sudden noises
- cries, startles, or jumps to sudden, very loud noises
- quiets when spoken to
- ceases activity when there is a new sound (example stops sucking)
- calms to familiar voices
- gurgles, coos, and laughs
- has different cries for different needs
3 TO 6 MONTHS
- turns eyes and head to search for the location of sound
- responds to mother's voice
- enjoys rattles and other sound-making toys
- enjoys babbling and has a large variety of babbling sounds
- makes sounds like /da/, /ga/, /ba/
- changes voice pitch
6 TO 10 MONTHS
- turns to and attempts to find sounds outside of visual field
- responds to own name, telephone ringing and someone's voice
- understands common words like "bye-bye"
- listens to music or singing
- makes sounds with rising and falling inflections
- vocalise using longer strings of consonant and vowel sounds together
10 TO 15 MONTHS
- turns to find a sound behind, below and to the side
- can point to or look at familiar objects or people when asked to do so
- imitates simple sounds and words
- jabbers to human voice
15 TO 18 MONTHS
- can hear and respond when called from another room
- bounces in rhythm with music
- uses adult-like intonation patterns
- can follow simple spoken directions
- identifies people, body parts, and toys on request
- gestures with speech appropriately
- child localizes sounds at all angles
- listens to stories
- recognizes sounds in the environment
- speaks in understandable two-word phrases
- uses about 50 words and has a receptive vocabulary of about 300 words
By 24 MONTHS
- should be able to sit and listen to read-aloud story books
- spoken vocabulary should be 200-300 words
- emergence of simple sentences
- most speech should be understandable to adults who are not with the child daily
3 TO 5 YEARS
- should understand nearly all that is said
- speech sounds should be clear and understandable
- spoken language should be used constantly
- vocabulary grows from 1000 to 2000 words
- uses complex and meaningful sentence
Types of Hearing Loss
There are 3 types of hearing loss that can affect your child. They are:
- Conductive Hearing Loss
- Sensorineural Hearing Loss
- Mixed Hearing Loss
Conductive hearing loss
With Conductive hearing loss some conditions affect the outer and/or the middle ear. Such interference in the transmission of the sound from the external auditory canal to the inner ear will cause conductive hearing loss. For example, an ear infection (otitis media) or a problem with any of the 3 ossicles can cause a conductive hearing loss. The child perceives a reduction in sound level which reduces the ability to hear quiet or faint sounds. This loss of hearing can usually be corrected medically or surgically.
Sensorineural Hearing Loss
Sensorineural Hearing Loss is a result of damage in the inner ear including the cochlea and/or the auditory nerve. For example, familial inheritance, viral/bacterial infections can cause a sensorineural hearing loss. Both loudness (ability to hear) and clarity (ability to understand) words vary with the degree and configuration of hearing loss. This type of loss is permanent and irreversible.
Mixed Hearing Loss
Mixed Hearing Loss is a result of a combination of factors which affect the outer and/or middle ear, and the inner ear.
Hearing loss can be described as a unilateral hearing loss, occurring in only one ear, or as a bilateral hearing loss occurring in both ears. If the loss occurs before or during birth or shortly after birth, but prior to the learning of speech and language, it is classified as congenital hearing loss. If the loss occurs anytime after birth, once speech and language have developed, it is referred to as acquired hearing loss. One of the most important considerations of any hearing loss is its degree. Commonly used terms to identify the severity of the impairment include slight/minimal, mild, moderate, moderately/severe, severe, and profound.
Hearing Impairment Degrees
- Minimal or slight hearing impairment: 16 to 25 dB HL for children
- Mild hearing impairment: 26 to 40 dB HL
- Moderate hearing impairment: 41 to 55 dB HL
- Moderately severe hearing impairment: 56 to 70 dB HL
- Severe hearing impairment: 71 to 90 dB HL
- Profound hearing impairment: 91 dB HL or greater
No hearing impairment is too slight not to warrant hearing management and no hearing impairment is too great to neglect the value of accessing residual hearing.
Speech and Language Development
Leading researcher and advocate for early identification of hearing loss in infants, Marion Downs stated:
One of the main tasks at birth, beyond basic survival, is combining all of the sensory inputs to develop the latent language potential that lies in every human organism. It is this potential for language that must concern us most because it is dependent on adequate functioning of the auditory system
(Source: Hayes & Northern, 1996, p. xii).
Hearing impaired children may not have immediate access to language, and may differ from their normal hearing peers in their language development. Language is used for communicating and serves as a basis for normal child development. Due to delays in the acquisition of these skills, the hearing impaired child may struggle with literacy, academic achievement, and social development.
Effects of hearing loss do not cause any one specific communication problem.
If your child has a hearing loss, the degree of hearing loss will impact on the audibility for some or all of the important acoustic speech cues. The Table below lists some of the possible effects on speech perception without amplification.
Source: Northern & Downs, 1991, p.14
Language develops so rapidly in the first few months of life that the longer an infant's hearing loss goes undetected, the worse the outcome is likely to be.
The type of hearing loss can also have effects on your child's speech and language development. The Table below shows the relationship between the two.
Source: Martin & Clark, 1996, p.5
My Child's Hearing Tests
A child of any age can be tested. If there are any concerns whatsoever, there is no child too young not to be tested. Early identification is the best head start that any parent can give his/her child.
An Audiologist will test your child's hearing. An Audiologist is a professional who holds a Masters Degree in Audiology, the science of hearing. The tests are non-invasive and will not hurt your child. The Audiologist will advise if your child has normal hearing. However, if a hearing loss is present, the Audiologist will explain the type and degree of hearing loss, and will recommend appropriate intervention strategies.
There are 4 tests that you can expect to have done on your child. Types of audiological evaluations:
- Behavioural hearing tests
- Auditory brainstem response
- Otoacoustic emissions
Behavioural Hearing Tests
These tests require the child to respond to soft sounds in some way. Both the parent and the child will be seated in a sound-treated room. When evaluating a baby or toddler, a head-turn response to a sound signal from a speaker is usually the best and most reliable testing method. This is called visual reinforcement audiometry. For the older child, 3 to 5 years, the test can be fun as the responses are based through games such as placing a peg in a board or raising the hand when a sound is heard. This is called play audiometry.
Also called Acoustic Immittance testing, this test helps determine how well your child's eardrum and middle ear are working. A probe tip is inserted into your child's ear canal delivering a gentle puff of air. Eardrum movement is recorded. If, for example, the eardrum does not move, it could mean that there is a middle ear infection. If there is negative pressure, it could mean the child is at risk for developing one.
Auditory Brainstem Response (ABR)
This is a more objective hearing test that can be help determine your child's hearing abilities. Clicks or tonal pips are sounded into your child's ear through headphones and the signals are picked up through electrodes. The responses are recorded and provide an estimate of your child's hearing sensitivity which can be compared to the results found on behavioural tests. The test measures the function of the auditory pathway leading to the level of the brainstem. Learn more about Auditory Brainstem Response testing.
Otoacoustic Emissions (OAE)
Another objective test, OAEs measure the function of the cochlea, the inner organ of hearing. The sounds are sent to your child's ear by inserting a probe tip in the ear canal. A tiny microphone picks up the response to the sound from the cochlea. This is like ‘hearing in reverse'. Learn more about Otoacoustic Emissions testing.
After a Hearing Loss is Confirmed
After a hearing loss is confirmed, the process of (re)habilitation begins. Research has shown that early intervention results in improved speech and language development, better communication skills, and higher educational achievement.
Discussions with the parents will include some of the following:
- parental involvement and responsibilities
- technological assistance
- speech and language interventions
- education for the hearing impaired child
Parental Involvement and Responsibilities
The importance of parental involvement is crucial for your child's overall success. In fact, your involvement is imperative particularly in your child's first 5 years of life. Long-term follow-up of children with hearing loss is usually required. You will be working closely with a communication disorders team, which may include Speech-Language Pathologists, Teachers for the Hearing Impaired, Hearing Instrument Dispensers, and Audiologists.
As a parent, you need to...
- Accept and understand your child's hearing loss
- Have realistic expectations of the various therapeutic interventions
- Appreciate the importance in keeping medical and educational appointments
- Provide daily stimulation and use good communication skills by encouraging conversations under all circumstances
Education for the Hearing Impaired Child
There are no single methodology that works for all hearing impaired children. The three main philosophies of education for the hearing impaired are oral, manual, and total communication. The oral/auditory method is used to describe programs that use spoken language by itself for communication and teaching. Manual communication is a nomenclature use to refer to programs that contain signs and/or finger spelling. The total communication method is used to describe the simultaneous use of speech and signs with finger spelling. The Educational Audiologist, the Speech-Language Pathologist or others may recommend the most appropriate method of teaching your child. Recommendations are generally based on the results obtained from various standardized speech and language tests that will help predict your child's best success.
Early intervention is critical - the earlier the better!
An aural (re)habilitation program is developed based on the degree, configuration, onset, and nature of your child's hearing loss. Early amplification intervention is fundamental to the success of auditory-based (re)habilitation programs. To minimize the effects of auditory deprivation and to maximize residual hearing usage, the early fitting of amplification is paramount.
Post-auricular or behind-the-ear (BTE) hearing aids are the most often recommended style of hearing aids for children. These hearing aids are coupled to earmolds that are custom made to your child's ears. A child's ear continues to grow so that earmolds can be replaced frequently at a relatively low cost. BTE hearing aids are built sturdier, provide easy access to caregivers, yet at the same time, have childproof features, and come in a multitude of cheerful colours.
Behind-the-ear hearing aids are also chosen because of FM system compatibility. The FM system allows your child to hear better in background noise. The speaker (Parent, Teacher, Speech-Language Pathologist) wears an FM transmitter with the voice being transmitted wirelessly to your child's FM receivers that are coupled to their hearing aids. A better signal-to-noise ratio is achieved, or in other words, the speaker's voice is heard above the level of the background noise and is not as affected by the distance at which the speaker is located.
Other technological solutions may involve surgery and can include bone-anchored hearing aids (BAHA) or cochlear implants. The BAHA's sound processor is attached to a tiny titanium apparatus that is surgically inserted in the bone behind the ear. Another surgically inserted device is the cochlear implant, an electrode array with an external speech processor that can be body worn or worn behind the ear like a hearing aid.
Speech and Language Interventions
Language serves as a foundation for later reading and academic skills. It is well documented that an established risk exists for speech and language delay in hearing impaired children. A Speech Language Pathologist will assess your child's development and provide direct therapy along with home suggestions as part of a speech and language treatment plan that will include auditory learning, speech production training, and language intervention programs. With the help of speech and language therapy, children who receive early amplification are able to develop speech and language skills that are comparable to their hearing peers.
Hearing Healthcare for the Whole Family