Keyfacts - Prevention of ear conditions Ear health workers web resource What are the different types of hearing loss? There are three types of hearing loss, sensorineural, conductive or mixed. Sensorineural hearing loss relates to damage to the hair cells in the inner ear, auditory nerve or brain. Sensorineural hearing loss can be caused by: exposure to loud noises, ageing, meningitis, viruses, genetic factors, certain drugs, certain pre-natal conditions. Usually sensorineural hearing loss is permanent. People with sensorineural hearing loss can be helped with amplification (hearing aids). How is hearing loss measured? It is the audiologist s job to work out if a patient has a normal range of hearing. A person may have normal hearing or slight, mild, moderate, moderately severe or profound hearing loss. Slight (16-25db) Understand conversation at 3m Speech and language development may be affected because of hearing loss Should understand most classroom discussion Conductive hearing loss relates to a problem in the transmission A child may require some degree of of sound through the outer and middle ear. Conductive hearing loss can be caused by: wax blockage, perforated eardrum, various forms of otitis media (OM), otosclerosis (abnormal growth of bone in the ear), or a break in one of the middle ear bones. Many of the conductive hearing losses can be medically or surgically treated. Some people with conductive hearing loss use amplification. amplification Mixed hearing loss involves both conductive and sensorineural hearing loss. What is audiology? Audiology is the study of hearing, balance and related disorders. Who should be referred to an audiologist for a hearing assessment? Children with recurrent, persistent and chronic OM conditions for more than 3 months should be seen by an audiologist. CORE FUNDING Mild (26-40db) Understand conversation at 1-1.5m May have delayed speech/language development Will miss up to 50% of classroom discussions Will need amplification, hearing aids or FM system May need special education attention
Moderate (41 55db) Understand conversation at 0.5m Will have difficulty at school Likely to have speech and language delay Will require hearing aids and/or FM system Will need special education and training for listening What happens in a hearing test? In a hearing test sounds are played at a particular frequency (pitch) at different intensities (volume) usually increasing from soft to loud. When the person hears the sound they raise their hand or press a button to let the audiologist know they have heard the sound. If the patient can hear the sound 2 times out of 3, the audiologist plots the intensity and the frequency of the sound on an audiogram. The actual values plotted on a audiogram are called thresholds. Moderately severe (56-70db) Severe (71 90dB) Profound Uses vision for additional cues to understand spoken messages May understand speech at 25cm Will hear moderately loud environmental sounds Will have delayed speech/language Requires use of hearing Will need special education and training for listening May understand speech at <15cm Hears loud environmental sounds Will have delayed speech / language Requires use of hearing aids and FM systems Requires auditory training Uses vision for additional cues to understand spoken messages Speech / language may not develop spontaneously if hearing loss was present before 1 year old May need cochlear implantation May only be aware of very loud sounds Speech and language will be defective Visual and gestural cues essential for learning Needs full time special education Requires use of hearing aids and FM systems May need cochlear implantation What is an audiogram? Across the top of the audiogram are numbers representing the frequencies of sounds that are to be tested. Low frequency sounds are on the left and high frequency sounds are on the right. Frequencies are measured in hertz (Hz) or kilohertz (KHz). This audiogram form depicts frequencies in Hz. The range of frequencies on this audiogram match the range of frequencies for general speech. The figure shows the ranges of the different types of hearing loss. Along the left hand side of the audiogram is the intensity scale in decibels. Softer sounds are represented at the top of the audiogram and louder sounds are at the bottom. ISO stands for International Standards Organisation which is a worldwide association that sets standards for many physical measurements. What are air and bone conduction tests? Air and bone conduction tests are used to work out what type of hearing loss a person might have. In an air conduction test a child wears ear phones to listen to specific sounds transmitted through the air. Air conduction tests assess the functioning of the outer, 2 Copyright 2013 Australian Indigenous HealthInfoNet
Keyfacts - Hearing and education middle and inner ear. In a bone conduction test a small bone vibrator is placed on the mastoid prominence behind the auricle (raised area behind the external ear). The bone vibrator transmits sounds to the bones of the skull which stimulates the inner ear directly. Bone conduction testing assesses functioning of the inner ear only. Comparisons of air and bone conduction thresholds are used to determine the type of hearing loss. Sensorineural hearing loss is defined as a difference of 15dB or less between the air conduction thresholds and the bone conduction thresholds of a given ear, and the air and bone conduction thresholds are worse (higher) than 15dB. Conductive hearing loss is when bone conductor thresholds are 15dB better (lower) than air conduction thresholds and the bone conduction thresholds are 15dB or less. What is masking? Masking is used to prevent the non-testing ear from hearing the sound tests. An unmasked signal of a high enough intensity presented to the test ear can cross over and be heard by the nontest ear. Masking is necessary if there is a 40dB difference in the air conduction threshold of the test ear and the bone conduction threshold of the non-test ear. Masking is almost always necessary when testing bone conduction. Bone conducted sounds are transmitted equally by the bones of the skull to both ears. What are the audiometric symbols? There are certain symbols to indicate if test results are from the right or left ear, and whether tests have been masked or not. Sometimes the symbols will be colour coded with red representing the right ear and blue representing the left ear. Any of the above symbols with an arrow pointing downwards means that there was no response at that frequency. Most audiograms will contain a key to all the audiometric symbols. http://www.healthinfonet.ecu.edu.au/earworkers 3
What impact does OM have on hearing? There is some uncertainty about the degree of hearing loss associated with different forms of OM, but it is generally agreed that children with persistent OME, recurrent AOM or a perforation (wet or dry) for more than three months are likely to suffer from significant effects of hearing loss and should be referred to an audiologist and an ear, nose and throat (ENT) specialist. A hearing loss of 35dB or more in the better ear is considered disabling, but even a loss of 20dB occurring during speech development and early schooling may have negative social and educational consequences. How can parents know if their child has hearing loss? Below are some key questions to ask parents to see if their child has hearing loss. New born to 4 months Do sudden loud noises wake the baby? Does the baby cry at very loud noises? Does the baby jump at sudden loud noises like the door slamming or dog barking nearby? 3-4 months Does the baby sometimes turns its eyes and start to turn its head to see where a noise comes from? Is the baby distracted from feeding by moderately loud noises close by? 4-7 months Does the baby turn often turn to straight sounds? Does the baby make a variety of babbling sounds? Does the baby enjoy playing with noisy toys or objects? Can you soothe the baby with your voice? 7-9 months Does the baby turn to find things heard but not seen? Does the baby gurgle, coo or babble to unseen sources of voices or other sounds? 9-24 months Does the baby respond to hearing sounds like the bath running, food being prepared or other children coming home? Does the baby copy words and sounds? Does the baby by about 15 months use some single words spontaneously? Does the baby respond when you call from another room? 2 3 years Does the child talk in 3 word sentences? Are you able to have a conversation with the child? 6 years and over Does the child sit too close to the television? Does the child respond to you when you call them from a distance or when they have their back to you? Does your child have trouble listening in noisy places i.e. people chatting in the background? How can parents improve communication and learning at home for children with hearing loss? Parents need to be aware of ways to communicate more effectively with children with hearing loss i.e. speak face to face. Parents also need to be aware of situations where a child s listening may be affected i.e. people talking in the background. It is important that parents encourage the use of language and speech at home. Reading, writing, singing and telling stories should be encouraged in children. Parents can also help by participating in their child s learning at child care and preschool. How can teachers improve communication in the classroom for children with hearing loss? Children with partial hearing loss can have problems hearing in a noisy classroom. Teachers should try to reduce background noises such as: people talking and moving, outside traffic, air conditioners and building site operations. Children with hearing loss should sit at the front of the classroom and the teacher should try to use as 4 Copyright 2013 Australian Indigenous HealthInfoNet
Keyfacts - Hearing and education much face to face communication as possible. The use of hands and facial expressions can also be helpful. English is a second language for many Indigenous children. Teachers should be aware of using new words and ideas in English that may be unfamiliar to Indigenous children. Writing key vocabulary on the board and using pictures or objects are useful ways to communicate new ideas. Teachers can also ask other students to help give prompts to children with hearing loss. Further reading Coates H, Vijayasekaran S, Mackendrick A, Leidwinger L, et al. (2008) Aboriginal ear health manual. Perth, WA: Abbott & Co Printers http://www.healthinfonet.ecu.edu.au/earworkers 5
Director Professor Neil Thomson Address Australian Indigenous HealthInfoNet Edith Cowan University 2 Bradford Street Mount Lawley, WA 6050 The Australian Indigenous HealthInfoNet is an innovative Internet resource that contributes to closing the gap in health between Indigenous and other Australians by informing practice and policy in Indigenous health. Telephone (08) 9370 6336 Facsimile (08) 9370 6022 Email healthinfonet@ecu.edu.au Two concepts underpin the HealthInfoNet s work. The first is evidence-informed decision-making, whereby practitioners and policy-makers have access to the best available research and other information. This concept is linked with that of translational research (TR), which involves making research and other information available in a form that has immediate, practical utility. Implementation of these two concepts involves synthesis, exchange and ethical application of knowledge through ongoing interaction with key stakeholders. Web www.healthinfonet.ecu.edu.au Australian Indigenous HealthInfoNet The HealthInfoNet s work in TR at a population-health level, in which it is at the forefront internationally, addresses the knowledge needs of a wide range of potential users, including policy-makers, health service providers, program managers, clinicians, Indigenous health workers, and other health professionals. The HealthInfoNet also provides easyto-read and summarised material for students and the general community. The HealthInfoNet encourages and supports informationsharing among practitioners, policy-makers and others working to improve Indigenous health its free on line yarning places enable people across the country to share information, knowledge and experience. The HealthInfoNet is funded mainly by the Australian Department of Health and Ageing. Its award-winning web resource (www. healthinfonet.ecu.edu.au) is free and available to everyone. F e at u r e d A rt wo r k Untitled by Donna Lei Rioli Australian Indigenous HealthInfoNet 2013 This product, excluding the Australian Indigenous HealthInfoNet logo, artwork, and any material owned by a third party or protected by a trademark, has been released under a Creative Commons BY-NC-ND 3.0 (CC BY-NC-ND 3.0) licence. Excluded material owned by third parties may include, for example, design and layout, images obtained under licence from third parties and signatures. CORE FUNDING