Surida Booysen
Sound waves are meaningless until they are processed by the auditory cortex where these electrical impulses are interpreted and meaning is given to these sounds.
We know constant stimulation is required for the brain to develop and this is why paediatric hearing loss is referred to as a neurodevelopmental emergency. This is why whenever people ask me what I do, my answer is either that I work with the brain or that I am a magician... I use the ears and hearing as a tool to optimise brain development in young children.
Children with normal hearing (0 – 15 decibels across all frequencies) learn up to 85 percent of information through incidental listening (over hearing). This ability allows them to constantly develop and stimulate their auditory cortex for language and communication with no direct instruction to learn new concepts and vocabulary.
A child with hearing loss does not have this capacity, even a mild hearing loss can cause the sound to be softer and unclear. As a result, children with hearing loss require direct teaching of most skills and knowledge that other children learn through incidental listening.
At the recent Carel du Toit Centre’s Ndiyeva (I can hear) Conference, Professor Anu Sharma from the Institute of Cognitive Science at the University of Colorado presented her research done on brain plasticity which confirms that there is a sensitive period for the auditory cortex in the first 3.5 years of life.
In other words, if an infant is born with hearing loss and the auditory cortex is not stimulated during this period, then the auditory centres of the brain may never again be used for what it was intended to do as the brain starts to reorganise itself.
The visual cortex will attempt to take over the auditory part of the brain and that is why some children with hearing loss become so visual.
A very good example of this brain reorganisation is seen in blind children who have a sharp sense of hearing.
“Grab the brain early enough, and the doors to learning and the universe remain open,” says Sharma.
Children with hearing loss need to receive appropriate intervention to language learning and access to sound through amplification technology as soon as possible.
Currently the profession is lobbying for universal newborn hearing screening, early identification and early intervention.
All children should have the same opportunity for cognitive development, despite their inherent difficulties and their family’s chosen communication modes.
Hearing is tested via different methods and measures, the hearing evaluation results are plotted on a graph called an audiogram.
The audiogram shows the softest sound an individual can hear in each ear at all important frequencies, particular those frequencies necessary for understanding speech (this is often referred to as the speech banana on an audiogram).
Anything below 15 decibels is indicative of a possible hearing loss and will most likely, depending on the cause of the hearing loss, need hearing technology. The further down the markings are, the worse the degree of hearing loss (See page 4).
It is crucial for a child to have immediate access to the following once hearing loss has been confirmed by a qualified audiologist:
l Immediate Action: Children who use a visual mode primarily for language development will not be able to fully develop their auditory skills at a later date, even if they are fitted with appropriate amplification since brain reorganisation may take place.
l Appropriate Amplification: This depends on the degree of hearing loss and the audiologist will guide the family to make the best choice of amplification technology, including hearing aids, cochlear implants, bone anchored hearing aids, brainstem implants, personal FM systems.
l Immediate access to family- centred intervention: Children’s brains are wired for learning at a very young age and it is crucial to enable parents and other family members with the appropriate skills to facilitate language development and auditory rehabilitation.
Family involvement is critical for the facilitation of natural language acquisition. The more input the child receives the better speech, language, comprehension and cognitive development will take place. Remember; the quality of the input determines the quality of the output.
l Team approach: Children with hearing loss often need additional support from other professionals such as an occupational therapist to assist with sensory processing and speech therapist to assist with speech and language development.
l Parent support: More than 95 percent of children with hearing loss are born into families with hearing parents. Grief, shock, fear and denial are all natural responses for hearing parents when their child is diagnosed with a hearing impairment.
Parents find a lot of strength and support from parents who have had to walk a similar journey.
l Role model: As children with hearing loss grow older, it is important to have friends who share in their experiences and guide them on the road ahead.
Some signs and symptoms that your child may have hearing loss:
l Your baby doesn’t startle at loud noises by one month.
l Your baby doesn’t turn to the source of a sound by three to four months of age
l He doesn’t notice you until he sees you.
l She concentrates on gargling and other vibrating noises that he can feel, rather than experimenting with a wide variety of vowel sounds and consonants.
l Her speech is delayed or hard to understand, or she doesn’t say single words such as “dada” or “mama” by 12 or 15 months.
l She doesn’t always respond when called (this may be mistaken for inattention or resistance, but could be the result of a partial hearing loss).
l He seems to hear some sounds but not others (some hearing loss affects only high pitch sounds; some children have hearing loss only in one ear).
l She seems not only to hear poorly, but also has trouble holding her head steady, or is slow to sit or walk unsupported (in some children with sensorineural hearing loss, the part of the inner ear that provides information about balance and movement of the head is also damaged).
l Booysen is a paediatric audiologist who has been working with hearing impaired children and their families for over 10 years. She has presented the profession at various international conferences focusing on hearing loss in children and works at the Carel du Toit Centre.