hearing-tests-forhuman

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Hearing tests for babies and youngchildrenThis factsheet explains how the hearing ofnewborn babies is tested and when andhow hearing may be tested again at othertimes during childhood.

Why is the screening of babieshearing important?

In the UK, around 840 babies are borneach year with a permanent hearing lossin both ears. If not identified early, ahearing loss can seriously hinder languageacquisition and communicationdevelopment and have a long term impacton educational achievement, confidenceand social skills.

Research shows that with earlyidentification of a hearing problem and

appropriate support, a child can developsuch skills to their optimal potential.

It is not easy to predict whether a baby willbe born with a hearing difficulty. Some90% of hearing impaired babies are borninto families where there is no history ofdeafness.

For many years, the first hearing check ababy received was at the age of seven oreight months. The test used, which wasperformed by health visitors, was theInfant Distraction Test (IDT). As the testrelied on babies reacting appropriately tosounds, it was not very accurate andresulted in approximately 50% of babieswith a hearing loss failing to be identifieduntil eighteen months old, with a further25% remaining unidentified at three years.A consequence of this was that deafchildren were severely delayed in their

language acquisitionThe importance of early identification ofhearing loss has been accepted for many

years, but it is only in the last few that thetechnology has become available toobjectively determine a childs hearingability shortly after birth. This has led to thereplacement of the Infant Distraction Testwith Newborn Hearing ScreeningProgrammes throughout the UK.

What does newborn hearingscreening involve?

Newborn hearing screening uses twotests. The first test was developed in theUK and is called the AutomatedOtoacoustic Emissions Test (AOAE). Itfollowed the discovery in the late 1970sthat in response to sound heard by theear, the healthy ear itself produces an

echo known as an otoacoustic emission.The test involves placing a small ear-pieceinto a babys outer ear which sends outgentle clicking sounds. The echoresponses are then measured by acomputer and indicate if a baby has afunctioning middle and inner ear (cochlea).

The test is performed by a trainednewborn hearing screener in the first fewweeks of life, often before a baby leaves

the hospital, but sometimes at home or ina local clinic by a trained health visitor.

Parents remain with their baby while thetest is carried out and it takes only a fewminutes to produce the results. Noparticipation is required from the baby, andthey often sleep through the test unaware.

If the test does not show a clear response,it will be repeated. This does notnecessarily mean they have a hearing loss

as sometimes conditions at the time of thescreening are not right; a baby may be


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unsettled or there may still be fluid in theear canal from the birth.

If after the second AOAE a baby still doesnot show a clear response, they will bereferred for a second type of test called theautomated auditory brainstem response(AABR). This too can be performed whilst

a baby is sleeping and generally takesbetween five and thirty minutes to perform.

The AABR measures activity in thebrainstem (which processes sound signalson the route between the ear and thebrain) in response to sounds and involvesplacing three small sensors on the babyshead and neck and headphones on thebabys ears. A series of clicking sounds isthen played and a computer records the

brains response.Where a baby does not achieve a clearresponse to the AABR screen, they will bereferred to an audiologist for furtherhearing tests. The aim of these tests willbe to diagnose the type of hearing lossand the severity of it.

If a baby is cared for in a neonatalintensive care unit or a special care babyunit for more than 48 hrs then they will

receive both tests.

What are the benefits of newbornhearing screening?

With the new method of hearing screening,a child with a permanent hearing loss cannow be identified much earlier, within 4 to5 weeks of birth. This means a child canstart receiving appropriate support within

the first six months of life.

What happens if the tests identifya hearing loss?

Sometimes a baby may be suspected ofhaving a temporary hearing loss causedby a condition such as glue ear. In thiscase a babys hearing may initially bemonitored with hearing tests at regularintervals as this condition can clear upwithout any intervention. For furtherinformation, request the Deafness

Research UKEar Infections and glue earin children leaflet.

If a baby is found to have a permanenthearing loss, an audiologist will explain thedegree of deafness and discussappropriate management options with thefamily. These may include the fitting ofhearing aids or cochlear implants and theprovision of early intervention support.

In some cases it may be possible toidentify the cause of the hearing loss. Forexample, many cases of permanenthearing loss occur because of geneticchanges that have been passed on fromone or both parents. Research has so faridentified a number of genetic mutationsthat cause deafness. For more informationplease request a copy of the DeafnessResearch UK factsheet Genetics andDeafness.

Alongside audiologists and doctors, thereare a number of other professionals whowork with families where there has been adiagnosis of permanent hearing loss.These include teachers of the deaf andspeech and language therapists.

If a parent would like to consider the optionof cochlear implantation then their babywill be referred to a cochlear implant

centre for initial assessment of suitability.With earlier identification of deafness,babies as young as six months old arenow able to receive a cochlear implant.

For information about cochlear implantsplease request a copy of the DeafnessResearch UK factsheet on cochlearimplants.

Are other hearing tests carriedout in childhood?

A child will not have their hearing testedagain until they start school unless there iscause for concern. A generaldevelopmental assessment is conductedby a health visitor when a child is aroundtwo years of age. Among other things, thischecks speech development which cansometimes indicate a hearing problem. Ifthis is suspected, the childs hearing willbe checked at an audiology (hearing)

clinic.In some parts of the UK, children undergoanother general assessment at the age of


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three. Where this is carried out, it will bearranged by the childs health visitor.

In the UK, most children currently have ahearing assessment when they startschool, known as the School EntryHearing Screen (SES). It involves asweep test which is a modified form of the

most common method of hearing testingknown as Pure Tone Audiometry (PTA).See the hearing test section below forfurther explanation.

If there are any concerns following thisscreening a child will be referred to a localaudiology clinic for further hearing tests.

As babies and children can develop oracquire a hearing loss, it is important thatyou think carefully about your childshearing and speech and share anyconcerns you have with your health visitoror family doctor.

Parents are the most likely people tonotice the development of hearing loss intheir children. Therefore it is very importantto request a hearing test at any time if youhave concerns about your childs hearing.

What are the signs to look out

for?Symptoms of hearing loss in children areeasily mistaken, but signs can be that thechild:

Doesnt react when called

Appears inattentive or prone todaydreaming

Listens to the TV at high volumes

Talks too loudly

Mispronounces words

Becomes unsettled at school

Is often tired, grumpy, frustrated orover-active

If your childs language development isslower than siblings or other children thesame age, it is important to have theirhearing assessed to rule out hearing loss

as a cause

What other kinds of test might mychild have?

If a hearing loss is suspected and a child isreferred to an audiology clinic some of thefollowing tests may be carried out. A childidentified with a hearing loss may have

hearing tests repeated at intervals thatenable their hearing to be monitored. If achild has hearing aids, this will enable anaudiologist to ensure the hearing aids aregiving maximum benefit.

Visual Reinforcement Audiometry(VRA) This is generally used withchildren from the age of six months olduntil two or three years. It uses anaudiometer, a machine used to measurehearing, to play sounds of different

volumes and frequencies throughloudspeakers.

When a child is at first presented with asound, they are encouraged to respondand turn towards the source by beingpresented with a visual reward such as atoy lighting up.

After this process is repeated a few timesand a child has associated theidentification of a sound with a visualreward the test can be used to identify thequietest sounds a child can hear. It canalso be used with small earphones to testeach ear individually.

Play Audiometry This may be used withchildren from around the age of two and ahalf years. It again uses an audiometer toplay sounds through a loudspeaker orheadphones.

A child is shown how to respond to asound they hear by performing a simpletask such as placing a peg in a board.They are then presented with furthersounds at different volumes andfrequencies.

Pure Tone Audiometry This can beused with children over the age of threeyears. Sounds are played throughheadphones and the child is asked torespond when they hear them, for example

by pressing a button.


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In the case of the school entry sweeptest, this checks whether a child can hearfour frequencies (high to low) at a set levelof loudness.

Most children with a severe or profoundhearing loss will already have beenidentified, but the test is useful to pick up

progressive deafness, which may not havebeen apparent before, as well as mild orone-sided problems.

The test can also help identify childrenwith glue ear, which causes temporaryhearing loss.

Bone Conduction AudiometrySometimes the above audiometry tests arealso carried out using a small vibratingdevice placed behind a childs ear so thatsound can be transferred through the bonedirectly to the inner ear.

By comparing the results of these tests it ispossible to see whether a hearing loss isdue to a middle ear or inner ear problem.

Speech discrimination test This test isused to assess a childs ability to hearwords without any visual information tohelp. Younger (pre-school) children areasked to identify pictures, toys or objects,while older children may be asked torepeat words or sentences. The wordsmay be played through headphones or aloudspeaker, or spoken to the child. Fromthis, the tester can identify the quietestlevel at which the child can correctlyidentify the words used.

Tympanometry This is a test which canbe used on children of all ages to find outhow flexible the eardrum is. For good

hearing the eardrum needs to be flexible inorder for it to pass the vibrations createdby sound waves through to the middle earspace, and from there into the inner ear. Ifthe eardrum is rigid (e.g. if there is fluidglue trapped behind it) it will not vibratewell enough to do this.

To perform tympanometry, a small tubewith a soft rubber tip is placed at theentrance to the ear canal. The air pressure

in the external canal is varied and theability of the eardrum to move ismeasured. If there is little movement of the

eardrum, this is an indication that the childis likely to have glue ear.

What research has beenconducted into newborn hearingscreening?

Deafness Research UK has been at the

forefront of hearingscreening technologyfor over a decade, developing thepioneering otoacoustic emissions testingmethods which are now revolutionisingscreening programmes worldwide.

In 1988, Deafness Research UKfunded the development of theILO88 otoacoustic emissionanalyser, a milestone in thedevelopment of screening

technology.

Deafness Research UK funded anearly pilot of the new screeningprogramme in Wessex. The resultsgained from this study were of greatvalue in developing plans for anationwide screening programme.

Deafness Research UK supportedthe production of guidelines on bestpractice to ensure that, as universal

screening programmes wereintroduced across the UK, allfamilies could expect the same highstandards of service.

Deafness Research UK is continuing itswork to improve newborn hearingscreening. The existing methods forscreening hearing in babies, as describedabove, are designed to detect deafnessarising from damage to the inner ear, or

cochlea.However, these methods do not pick updeafness which results from damage tothe area of the brain that processeshearing (the auditory cortex) or to thebrainstem. This kind of deafness is knownas central hearing impairment.

Babies who are born prematurely are atparticularly high risk of central hearingimpairment because they frequently suffer

perinatal asphyxia (a lack of oxygen duringlabour or delivery) which can damage thebrainstem.


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Deafness Research UK supported aproject to assess how well a new testworks for detecting central hearingimpairment early, in babies who havesuffered perinatal asphyxia.

The test, called the maximum lengthsequence brainstem auditory evoked

response (MLS BAER) involved playing acomplex sequence of sounds to sleepingbabies while recording the electricalactivity caused by the brain in response tothe sounds, using three small sensorsplace on the babies head and ears.

Results showed that MLS BAER test candetect damage to the brainstem fromperinatal asphyxia during the first monthafter birth. This could be very important for

early therapeutic intervention to preventfurther damage.

Deafness Research UK funded a study toimprove the test for finding out what sort ofhearing loss a baby has. A bone-conduction test uses a device to presentsounds to the cochlea while bypassing theouter and middle ear. This can be used toreveal whether there is hearing impairmentdue to the inner ear alone.

The response to bone-conducted soundwas measured using the auditory steadystate response (ASSR) which picks up thebrains activity caused by changes involume of sounds. However problems withthe bone-conduction device previouslymeant that the sensors used to measurethe ASSR could pick up false signals thathid the true amount of hearing loss.

Results showed that changing the design

of bone-conductors to improved electricalshielding reduces the false signals. Thiswill mean that babies can be diagnosedmore accurately.

What research is currently beingundertaken?

Deafness Research UK has also beenactive to find out the effects of beingidentified early by the newborn hearingscreening programme.

Positive Support in the Lives of DeafChildren and Their Families is a project

that explores how different interventionssuch as provision of hearing aids, the roleof the family and professional support(including education and health services)can affect the development of a deaf child.

The four year study, supported by theNational Lottery through the Big Lottery

Fund is a partnership between DeafnessResearch UK, the University ofManchester, University College Londonand the National DeafChildrens Society.Results from the study have beenpublished and have proved conclusivelythat if babies have assistance in the first 6months of their life, the languagedevelopment of the child improvesenormously in comparison to a child thathas help later in their childhood.

Who should I contact for moreinformation?

If any of your questions concerninghearing tests for babies and children havenot been answered by reading thisfactsheet, contact the Deafness ResearchUK Information and Advisory Service forfurther assistance. Our Information teamwill either answer your enquiry directly or

refer it to one of our scientific or medicaladvisers.

Open: 9.30 a.m. to 5.30 p.m., Monday toFriday (a message can be left at othertimes).

Freephone: 0808 808 2222

E-mail:[email protected] click the ask question option from ourwebsite homepage:

www.deafnessresearch.org.ukFor further information about the NewbornHearing Screening Programmes in the UKvisit:

England:

www.hearing.screening.nhs.uk

Scotland:http://www.nsd.scot.nhs.uk/services/scree

ning/unhearingscreening/index.html
mailto:[email protected]:[email protected]:[email protected]://www.deafnessresearch.org.uk/http://www.deafnessresearch.org.uk/http://www.hearing.screening.nhs.uk/http://www.hearing.screening.nhs.uk/http://www.nsd.scot.nhs.uk/services/screening/unhearingscreening/index.htmlhttp://www.nsd.scot.nhs.uk/services/screening/unhearingscreening/index.htmlhttp://www.nsd.scot.nhs.uk/services/screening/unhearingscreening/index.htmlhttp://www.nsd.scot.nhs.uk/services/screening/unhearingscreening/index.htmlhttp://www.nsd.scot.nhs.uk/services/screening/unhearingscreening/index.htmlhttp://www.hearing.screening.nhs.uk/http://www.deafnessresearch.org.uk/mailto:[email protected]


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Wales:

www.screeningservices.org.uk/nbhsw/

Northern Ireland contact:

Newborn Hearing Screening ProgrammeNorthern IrelandChildrens Audiology

Level 7D, Outpatients DepartmentEye and Ear BuildingRoyal Victoria HospitalBelfastBT12 6BATel: 028 9063 3558

For a wide range of information and adviceabout childhood deafness contact:

National Deaf Childrens Society(NDCS)

15 Dufferin Street, London, EC1Y 8UR

Helpline: 0808 800 8880 (freephone, voiceand textphone)

Fax: 020 7251 5020

Website:www.ndcs.org.uk

Email:[email protected]

This factsheet has been produced by DeafnessResearch UK, in consultation with our medical andscientific advisers.

Whilst all reasonable efforts have been made toensure the information and advice given is takenfrom reputable sources and passed to the public ingood faith, no responsibility can be taken on thepart of Deafness Research UK or its advisers for

any error or omission.You should not act on any advice without firstreferring to your family doctor or another medicallyqualified adviser.

Updated: September 2010

Deafness Research UK is the onlynational medical research charitydedicated to helping people withdeafness, tinnitus or other hearingproblems.

Scientists are now predicting muchmore effective treatments for tinnitusand that a cure for some forms ofdeafness is not only possible but likelywithin the next few years. DeafnessResearch UK is at the forefront of thiswork.

You can support us by making adonation. For more information call uson 0207 164 2290 or write to:

Deafness Research UK, 330-332Grays Inn Rd, London WC1X 8EE

Charity no. 326915
http://www.screeningservices.org.uk/nbhsw/http://www.screeningservices.org.uk/nbhsw/http://www.ndcs.org.uk/http://www.ndcs.org.uk/http://www.ndcs.org.uk/mailto:[email protected]:[email protected]:[email protected]:[email protected]://www.ndcs.org.uk/http://www.screeningservices.org.uk/nbhsw/

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