Monday October 19th 2020

I hear you! Auditory development in babies

YOUR child is wired to the world through her ears – delicate, complex structures which filter and interpret a symphony of sounds and vibrations. Auditory health is strongly linked to good language and speech development and even a very mild hearing loss can affect her ability to speak and understand others.

From birth to pre-school, your child’s auditory world forms a critical part of her cognitive, social and emotional development.

Wired for sound – hearing in the womb

At about eight weeks, the embryo starts forming tiny ear structures which are structurally complete by roughly 24 weeks. The inner ear bones and nerve endings connected to the brain are in place at around 18 weeks, meaning that your baby can already hear the hustle and bustle of her noisy home. The womb is like a train station – it’s such a hive of activity! She hears your blood pumping, heart beating, food digesting, liquids gurgling and can even detect voices (especially yours).

From this point onwards, sounds become your baby’s main source of information.

The auditory system begins to function within the womb at 26 weeks, says Dr Maggi Soer, SUBS:CORRECT senior lecturer of audiology at the University of Pretoria’s department of communication pathology.

“Research has shown that babies are able to recognise their mother’s voice at birth and can also remember what they heard before birth. Babies recognise a story heard while still in the womb.”

Studies have also demonstrated how a baby’s heart rate reduces when listening to a familiar story, says Dr Soer.

During pregnancy, you’ll be aware of kicking and movement in response to sound – this is your baby’s instinctive reaction to loud noises, such as a balloon bursting or door slamming shut.

“This is why it is so important to protect your baby’s hearing even before birth. Exposure to noise, alcohol and ototoxic drugs during development of the cochlea and auditory mechanism may cause acoustic trauma and hearing loss.”

How important is hearing?

Hearing and listening form the “invisible cornerstones of spoken communication”, according to the South African Association of Audiologists.

Babies and toddlers spend a large portion of their day in active or passive listening activities. This is a primary means of gaining information about their environments.

“The importance of hearing to the communication and learning process tends to be significantly underestimated because hearing impairment is invisible; thus the effects of hearing impairment often are associated with problems or causes other than the hearing impairment,” the Association says.

Pivotal to any educational programming using speech as communication is the management and assessment of your child’s listening ability and hearing sensitivity.

At approximately six months, babies have already learned all the basic sounds of their native language, says Dr Soer.

A baby who is deprived of appropriate language stimulation during the first years of life will never fully attain his or her best potential language function, whether the deprivation is from lack of hearing or lack of high-quality language experience.

How hearing works

The human ear comprises external, middle and inner structures.

Sound is collected by the visible part of the ear (the pinna) and then directed into the outer ear canal.

The sound causes the eardrum to vibrate, which in turn sets in motion the vibration of three tiny bones in the middle ear – the hammer, anvil and stirrup.

This vibration transfers to the cochlea – which looks like a snail shell – in the inner ear. Very sensitive hairs line the cochlea and trigger nerve signals which are sent to the brain.

Hearing development – a checklist

As children, we learn about speech and language by listening to other people. For this reason, the first few years of childhood are vitally important for development in these key areas. Early detection of any hearing loss is therefore crucial.

At each developmental stage, there are several indications that your baby or child is hearing properly:

Birth to six months

  • Moves her head, arms, legs and eyes in response to noises or voices
  • Looks about her to see where a sound is coming from
  • Responds to music
  • Startles, wakes up or cries in response to loud sounds
  • Smiles when you speak to her

Seven months to one year

  • Clearly listens
  • Babbles, takes turns with mom to speak, coos in response
  • Gives response to “no”
  • Looks up or turns around when name called
  • Knows basic words such as “mom” or “cup”
  • Responds to requests such as “come here”

One to two years

  • Imitates sounds, words and noises (such as animal noises) but still gestures a lot to communicate
  • Starts using 1 – 2 word sentences in latter part of age category
  • Recognises sounds such as a cell phone ringing
  • Follows simple commands such as “pick up your ball”
  • Will turn towards you when you stand behind her and call her name

Two to three years

  • Starts asking lots of questions (“where’s daddy?” and “what’s this?”)
  • Carries out two-step commands such as “pick up Teddy and put him on the chair”
  • Makes efforts at conversation, though you may not understand as she omits speech sounds from words
  • Will listen to a simple story

Three to four years

  • Answers simple questions
  • Creates sentences with four or more words
  • Will hear you if you call her from a different room
  • Comfortably listens to the television at the same volume level as everybody else

Four to five years

  • Listens attentively to a story and asks simple questions about it
  • Understands and hears most communication at both school and home
  • Will talk easily with grown-ups and other children

Making sense of sound

Babies need to exposed to a variety of experiences, accompanied by language stimulation, explains Dr Soer.

“The basis of natural language development is conversation. Talk to your child in a natural manner and react in a positive manner to communicative attempts.”

  • Play music! Your choice of melody isn’t restricted to the radio or CD player. Music is everywhere – it’s in the sound of rain on the roof, the clickety-click of heels on a tiled floor, the meow of a cat or the squawking echo of a bird overhead.
  • Talk up a storm. Long before birth, your child recognised and fell in love with your voice. Continue this close auditory relationship by talking to her one-on-one. Go for a walk and point out the flowers, leaves and trees; squish your toes in beach sand and talk about how it feels; tell her exactly what you are doing as you go about your chores, naming each grocery or clothing item.
  • Read it. This is not just a simple pleasure pursuit – reading helps your child develop four important thinking skills. These are the ability to pay attention, a good memory, problem solving capability and language proficiency. The best way to foster a love of books is to read aloud to her.
  • Tune in. You’re not the only one with a pair of ears – your baby is constantly aware of different sounds and vibrations too, so be aware of what she’s picking up and then comment on it. As you hear an aeroplane drone by, notice her reaction and then explain what she is hearing. Let her lead the way.
  • Turn it off. Television, computers, stereos and radios are a cacophony of sound that may in fact be quite meaningless sometimes. Rather stimulate her with natural sounds as much as possible – the swish of a broom, the chirp of birds during dawn patrol and most important of all – your voice.
  • Sing. Simple nursery rhymes become firm favourites as your child grows. Try the ones you remember from your own childhood, such as “Hey Diddle Diddle” or “Incy Wincy Spider”.
  • It’s the small things…the most boring tasks may be the most enriching. A few minutes of chatter while washing the dishes will introduce your baby to a host of new words such as water, dish, fork, plate, soap and cloth.
  • Simplify sound. No matter what clever marketing ploys will have you believe, specialised CDs or DVDs featuring baby-stimulating music and other whistles and bells are not necessary. Although educational toys are helpful, they are not crucial.

Hearing evaluation – a safety net

Newborns will likely have a hearing screening before being discharged from hospital, says medical doctor Robert O‘Reilly. If she doesn’t have the screening or was born at home or in a birthing centre, you should take her to your paediatrician or doctor for a test within three weeks.

Most children who are born with hearing loss can be diagnosed and subsequently treated as a result of early screening. However, hearing loss may also be caused by environmental factors such as trauma, loud noise or infection, so it’s important to have her hearing evaluated as she grows.

Remember – treatment for hearing loss is most effective when started by six months old. Experts suggest taking your child to an audiologist.

If she does not pass her newborn hearing screening, this does not necessarily mean that your child has a hearing loss, says Dr O’Reilly. Ear fluid or debris can interfere with the results and a re-test should be done within three months.

Children with normal hearing may be evaluated at the doctor and tests may be done at ages 4, 5, 6, 8, 10, 12, 15, 18, preferably by an audiologist.

There are various ways to test hearing and the choice depends on your child’s age, development and health.

Sounds of silence – hearing loss

Hearing loss is a common birth defect. About one to three out of every 1000 babies is likely to be born with some degree of hearing loss. In about half of all cases, no obvious cause is found.

“Parents are in the best position to identify their child’s hearing difficulties and physicians need to become more responsive to parents’ concerns,” says Dr Soer. “State agencies can help by initiating high-risk screening programmes.”

The good news is that hearing problems can be treated and early detection is key. Ideally, hearing loss should be diagnosed by the time your baby is three months old, which means it’s very important to have her hearing screened regularly from birth.

There are several red flags which may indicate possible hearing problems. These are :

  • stops early babbling
  • fluid drains from the ears
  • pulls her ears and is feverish and grumpy
  • has a lot of colds and ear infections
  • does not respond when called
  • speaks loudly
  • has trouble understanding a conversation in a crowded or noisy place
  • frequently asks for words or phrases to be repeated
  • does not understand someone unless the person is facing her
  • turns up the volume of the television or radio, disturbing others

The causes of hearing loss are varied. They include premature birth, high bilirubin requiring a transfusion, a family history of childhood hearing problems, regular ear infections or birth complications. Even brief exposure to loud noise or sounds can cause deafness.

“It is important to remember that there are professionally trained audiologists available with appropriate skills and equipment to evaluate the hearing of any child at any age with a high degree of accuracy,” says Dr Soer.

Facts about hearing loss

The South African Association of Audiologists says that the problem of hearing loss in children is significant when considering these sobering facts :

  • One in 1000 children is born with profound deafness
  • Two children in 1000 will acquire deafness in early childhood
  • Babies needing intensive medical care as newborns are at special risk for hearing loss, resulting in one child in 50 from the intensive care nurseries being hearing impaired
  • Ear infection, the most common infectious disease of childhood, may be associated with hearing loss
  • Nearly 100% of all children will develop some periods of hearing loss related to ear infection between birth and 11 years old

Who’s at risk? Apart from undetectable causes, there are eight risk factors which might indicate a potential hearing problem. These are a family history; ventilation for more than five days; hyperbilirubemia or yellow jaundice; presence of any syndrome associated with any type of hearing loss; presence or history of cleft palate; birth weight of less than 1500g; consumption of ototoxic medication and finally, history of neonatal meningitis.

The Association says that children must be evaluated audiologically if any of the following are present :

  • History of chronic otitis media (middle ear infection)
  • Complaints from the teacher regarding concentration and/or attention difficulties.
  • Children who often ask for repetition.
  • Children who often don’t hear when called from another room.
  • Slow speech and language development.
  • Parents who think their children do not hear 100%
  • Parents who are worried about their child’s hearing.
  • Other family members who have speech language and hearing problems
  • Any history of mumps, measles or meningitis.

There are two main types of hearing loss – conductive (interference in transmission of sound to cochlea or inner ear) and sensorineural (dysfunction, malformation or damage to inner ear or hearing nerve).

Babies and young children often develop conductive hearing loss because of ear infections, although the loss is usually medically or surgically treatable, mild and temporary.

“Unilateral hearing loss (involvement of one ear only) is a fairly common problem among children, with a prevalence of 3-13 in 1000 children,” explains Dr Soer.

“Total unilateral deafness is most commonly due to mumps developed in very early childhood. According to research, children with unilateral hearing loss experience considerably more difficulty in communication and in education than was previously supposed.”

For sensorineural hearing loss patients, the most common problem is cochlear (inner ear) hearing loss and usually presents from birth. Hereditary, caused by medical issues or showing no cause at all, this problem is usually permanent.

There are various treatments for hearing loss, with hearing aids being the preferred non-medical intervention, says Dr O’Reilly. Auditory or listening therapy, as well as speech (lip) reading is also successful alternatives.

Children with extreme hearing loss and who won’t benefit from a hearing aid may be offered a cochlear implant, which sends the sound information past a damaged cochlea to the hearing nerve.

TIP : If you think your child may have a hearing problem, talk to your family doctor. If required, you will be referred to an ear, nose, and throat specialist (otolaryngologist) or audiologist.

Ear infections – the risks and facts

Ear infection is considered to be the most common infectious disease of childhood and the most common cause of hearing loss, says Dr Soer.

An estimated 5 million school days are missed every year due to otitis media (middle ear infection) and nearly all children will develop some period of hearing loss related to ear infections from birth through ten years of age.

“Ten to 15% of children who receive hearing screening at school fail because they cannot hear within normal limits.”

The risk of developing speech and language problems increases with recurring ear infections. As many parents know, middle ear infections (otitis media) are very common in children, especially from birth to three years old.

Often starting with a cold, acute otitis media usually clears up quickly but can be very painful.

Otitis media with effusion – or OME – is a more worrying type of infection involving thick fluid that fills the middle ear. This blockage interferes with the transmission of sound and it’s likely that children will suffer a mild hearing loss as a result.

OME may take between a few weeks and several months to heal. Worryingly, up to 50% of OME infections are silent; this means that neither parents nor children are aware of symptoms and the problem remains untreated.

Since there’s usually no pain associated with OME, hearing loss is often the only sign that something is wrong. That said, one study concluded that a hearing loss doesn’t always occur and in 60% of cases, parents reported that they were unaware of any hearing problem.

If you suspect that your child has an ear infection, visit your doctor immediately. Should your child suffer from regular infections or fluid build-up in the middle ear, you may be referred to an audiologist or speech-language pathologist for further tests.

Audiologists are able to assess how severe the hearing loss is – even in children who are exceptionally young and difficult to test. Your visit to the speech-language pathologist will determine any particular language and speech skills needing attention, as well as recommended treatment.

There are various treatments for hearing loss, with hearing aids being the preferred non-medical intervention, says Dr O’Reilly. Auditory or listening therapy, as well as speech (lip) reading are also successful alternatives.

Children with extreme hearing loss and who won’t benefit from a hearing aid may be offered a cochlear implant, which sends the sound information past a damaged cochlea to the hearing nerve.

Chronic or recurring ear fluid and an attendant hearing problem might be a risk if your child displays any of the following

  • inattentiveness
  • wanting the television or radio louder than usual
  • misunderstanding directions
  • irritability without any particular cause
  • scratching at or pulling the ears
  • listlessness
  • ears draining fluid
  • stops early babbling
  • frequent ear infections and/or colds
  • doesn’t respond to you when you call
  • in loud or crowded places, has difficulty hearing you or following a conversation
  • says “what?” often and asks for words to be repeated
  • appears listless for no known reason

Whether she hears perfectly or has a hard time doing so, your child deserves the benefit of your full attention. Be aware of her world and how she’s interacting in it – her auditory capability has a profound impact on her identity and independence.

Resources

Dr Maggi Soer, Senior Lecturer of Audiology at the Department of Communication Pathology, University of Pretoria

South African Association of Audiologists : www.audiologysa.co.za TOLL FREE 0861 101 924 and to find an audiologist in your area

Child and Family (Canada) : http://www.cfc-efc.ca/docs/caslpa/00002_en.htm

Discovery Health (http://health.discovery.com)

http://parenting.ivillage.com/pregnancy/psecondtri/0,,midwife_3p4h,00.html

http://www.kidshealth.org/parent/general/eyes/hear.html

© Beth Cooper, 2010.

4 Comments for “I hear you! Auditory development in babies”

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