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LEARNER RESOURCE Audiometry – Assessment A 3064-9/HLSP Version No. 1 Community Services, Health, Tourism and Hospitality Division Health and Life Sciences Programs 3064-9/HLSP Audiometry – Assessment A V1 3064-9/HLSP Audiometry – Assessment A V1 i Acknowledgments TAFE NSW - Community Services, Health, Tourism and Hospitality Division would like to acknowledge the support and assistance of the following people in the production of this resource package: Writer: Jean Tsembis Audiologist TAFE NSW This learning guide is based on a previous learning guide written by Jean Tsembis and Janette Brazel. Project Manager: Gary Wood Program Manager Health and Life Sciences Programs Enquiries Enquiries about this and other publications can be made to: TAFE NSW - Community Services, Health, Tourism and Hospitality Division Locked Bag No. 6 MEADOWBANK NSW 2114 Tel: 02-9942 3200 Fax: 02-9942 3257 T:\aa Electronic Information System\Educational Delivery\Resources (Final Copy)\The Health Team\HEALTH and LIFE SCIENCES\Audiometry (Health&Life)\3064-9_HLSP_V1\3064-9_HLSP_Audiometry - Assessment A_V1.doc © Community Services, Health, Tourism and Hospitality Division TAFE NSW, 2004. Copyright of this material is reserved to Community Services, Health, Tourism and Hospitality Division, TAFE NSW. Reproduction or transmittal in whole or in part, other than for the purposes of private study or research, and subject to the provisions of the Copyright Act, is prohibited without the written authority of Community Services, Health, Tourism and Hospitality Division, TAFE NSW. ISBN 0 7348 1556 5 © 2004, TAFE NSW ii 3064-9/HLSP Audiometry – Assessment A V1 3064-9/HLSP Audiometry – Assessment A V1 iii RESOURCE EVALUATION FORM Please come back to this page when you have finished working on this resource and complete this form. Your feedback can assist us to continually improve this resource. Course Name _________________________________________ Course Number _________________ Campus _____________________________________________ Date at finish of module __________ Was your learning totally external, with occasional phone contact with a designated teacher? Yes No Was your learning externally supported by a study group of other students studying the same module? Yes No How many workshops were given to support your learning? ______ (Please give a number – none, 1, 2, 3) Did your learning involve class support material at the TAFE college? Did you find this resource easy to use? Yes Yes No No Any comments ___________________________________________________________________________________________ ___________________________________________________________________________________________ Was the content useful/clear/relevant? Yes No Any comments ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ Please comment on any ways this resource could be improved for future learners. ___________________________________________________________________________________________ ___________________________________________________________________________________________ What other resources did you find that helped you with your studies? ___________________________________________________________________________________________ ___________________________________________________________________________________________ Thank you for taking the time to give us your valuable feedback. Please give this to your teacher who will send it to: TAFE NSW - Community Services, Health, Tourism and Hospitality Division Locked Bag No. 6 MEADOWBANK NSW 2114 FAX: 02 9942 3257 iv 3064-9/HLSP Audiometry – Assessment A V1 3064-9/HLSP Audiometry – Assessment A V1 v TABLE OF CONTENTS INTRODUCTION TO THIS LEARNING RESOURCE ................................................ 1 SUGGESTED LEARNING RESOURCES .................................................................................... 2 Relevant texts ................................................................................................................. 2 Relevant Internet sites ................................................................................................... 3 ASSESSMENT OF HEARING .......................................................................................... 5 THE TEST ENVIRONMENT .................................................................................................... 5 SEATING THE CLIENT .......................................................................................................... 6 THE AUDIOMETER ............................................................................................................... 6 HEARING THRESHOLDS ....................................................................................................... 8 INSTRUCTING CLIENTS ........................................................................................................ 8 PLACING THE EARPHONES ................................................................................................... 9 AIR CONDUCTION ............................................................................................................. 10 BONE CONDUCTION .......................................................................................................... 12 AUDIOMETRIC WEBER ...................................................................................................... 14 CARHART’S NOTCH ........................................................................................................... 14 THE HUGHSON-WESTLAKE TECHNIQUE............................................................................ 15 SUMMARY ........................................................................................................................ 16 APPROPRIATE TECHNIQUES FOR DIFFERENT CLIENTS ........................................................ 16 THE PATTERN OF PRESENTATIONS .................................................................................... 17 LENGTH OF PRESENTATION ............................................................................................... 18 DEALING WITH CLIENTS WHO CAN’T / WON’T CO-OPERATE .............................................. 18 PLAY AUDIOMETRY .......................................................................................................... 20 TACTILE RESPONSES ......................................................................................................... 20 THE AUDIOGRAM .............................................................................................................. 21 TYPE AND DEGREE OF HEARING LOSS ............................................................................... 22 THE 3FAHL ..................................................................................................................... 24 SOME EXAMPLES OF AUDIOGRAMS WITH THEIR DESCRIPTIONS ......................................... 25 SPEECH AUDIOMETRY ................................................................................................ 33 CHECKING THE VALIDITY OF THE PURE TONE AUDIOGRAM ............................................... 34 DETERMINING SPEECH DISCRIMINATION ........................................................................... 34 ESTABLISHING REHABILITATION NEEDS ............................................................................ 35 DIAGNOSTICALLY ............................................................................................................. 35 CONVEYING RESULTS TO CLIENTS .................................................................................... 35 REFERRING CLIENTS ......................................................................................................... 37 MONITORING REFERRAL ................................................................................................... 38 WRITING REPORTS ............................................................................................................ 38 TOPIC QUESTIONS ........................................................................................................ 39 vi 3064-9/HLSP Audiometry – Assessment A V1 3064-9/HLSP Audiometry – Assessment A V1 1 INTRODUCTION TO THIS LEARNING RESOURCE This learning resource deals with the assessment of hearing. This is one of the recurring themes in the audiometry units of competency that are aligned to the Certificate IV in Audiometry HLT41302, which is a qualification of the Health Training Package HLT02. The units of competency that include this theme are: HLTAU1A – Conduct screening hearing tests for children HLTAU2A – Conduct screening hearing tests for adults HLTAU3A – Conduct hearing tests assessments. Assessment of hearing is part of the required knowledge that underpins the development of competence. This knowledge will help you to understand the effects of hearing impairment and its impact on rehabilitation. It will also help you in discussing results with other clinicians such as audiologists and doctors. The purpose of this learning resource is to provide you with fundamental knowledge, skills and attitudes to perform basic audiometric assessment. In your activities and assessments your teacher can reasonably ask you to: Describe recognised basic audiometric techniques for threshold assessment Determine the appropriate technique relevant to a client Perform basic audiometric techniques on clients Interpret and convey results of assessment to clients Record results and refer client as appropriate Monitor referral. Before starting this learning resource, it is recommended that you complete the learning resources that provide you with underpinning knowledge for effectively communicating with clients, dealing with clients in a safe manner and the basic principles of hearing mechanisms relevant to audiometry, i.e. anatomy, pathology and psychoacoustics. It is also recommended that you do the sections in the learning guide for Instrumentation that are concerned with audiometers and the sections dealing with taking a case history. After completing this learning resource you will be able to commence practicing hearing testing. You should spend some time practicing on colleagues, peers, friends and families. When you start clinical practice your supervisor can reasonably expect you to be able to take case histories, perform otoscopy and perform audiometry without masking. Therefore, you will need to be sure to have completed all the learning necessary to ensure that you have the relevant skills and knowledge. This learning resource is designed to complement your class or individual learning activities. You should use this resource as a guide to identify areas of learning. You cannot rely on this learning resource alone, you must use other sources of information. You may also be able to find some computer programs that help you practice performing audiometry. Check with your TAFE teacher for more advice. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 2 Suggested learning resources There is not a required textbook for this topic but there are many that can help you. The following textbooks are all relevant and you may decide to refer to them as you study this topic. Relevant texts TITLE AUTHOR PUB DATE PUBLISHER ISBN Clinical Audiology – An Introduction Stach, B.A. 1998 Singular Publishing Group Inc, San Diego 156593346X TITLE AUTHOR PUB DATE PUBLISHER ISBN Principles of Hearing Aid Audiology Maltby, M.Tate 2001 Whurr Publishers, UK 1861562578 TITLE AUTHOR PUB DATE PUBLISHER ISBN Introduction to Audiology Martin, F.N. & Clark, J.G. 8th Edition, 2003 Allyn & Bacon, USA 0-205-36641-4 TITLE AUTHOR PUB DATE PUBLISHER ISBN Audiology: the Fundamentals. Bess, F.H. & Humes, L.E. 2nd Edition, 1995 Williams & Wilkins, Baltimore. Md. 0683006207 TITLE AUTHOR PUB DATE PUBLISHER ISBN Basic Principles of Audiology Assessment Hannely, M. 1991 Prentice-Hall, USA 0205135528 TITLE AUTHOR PUB DATE PUBLISHER ISBN Audiology Newby, H. & Popelka, G.R. 6th edition, 1992 Allyn & Bacon, USA 0130519219 TITLE AUTHOR PUB DATE PUBLISHER ISBN Handbook of Clinical Audiology Katz, J. et al. 4th Edition, 1994 Williams & Wilkins, Baltimore. Md. 0683006207 Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 TITLE AUTHOR PUB DATE PUBLISHER ISBN TITLE AUTHOR PUB DATE PUBLISHER ISBN 3 Audiologists Desk Reference Volume I - Diagnostic Audiology Principles, Procedures and Protocols Hall, J.W. & Mueller, G.H. 1997 Singular Publishing Group, UK 156593269 Interactive Audiology, 1/e Frederick Martin and John Clark 2003 Allyn & Bacon 0205319475 NB: This is a CD-ROM AS/NZS 1269.4 – 1998: Occupational Noise Management: Auditory Assessment PUBLISHER Standards Australia ISBN 0733717667 CONTACT DETAILS: http://www.standards.com.au/catalogue/script/search.asp TITLE Relevant Internet sites There are many sites on the Internet that you can access using a search engine. As with all information, you need to cross check a variety of sources to establish its credibility. Many of the websites will help you to understand aspects of hearing loss from the client’s point of view. The sites that are listed below were accessed in September 2003. As internet sites and the information in them change, you may wish to perform your own search. http://members.fortunecity.com/michaelder/tableofcontents/audiometertopics.html Looks at some calibration issues and the difference between standard earphones and insert earphones. www.etymotic.com This is the site of Etymotic Research, the company that produces insert earphones and many other products. http://www.shhh.org/ The home page of the organisation Self Help for Hard of Hearing People. Provides lots of information about hearing loss. http://www.shhhaust.org/index.htm The home page of the Australian self help group Self Help for Hard of Hearing People. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 4 3064-9/HLSP Audiometry – Assessment A V1 Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 5 ASSESSMENT OF HEARING The basic audiometric assessment procedure is called pure tone audiometry. Before starting audiometric assessment you will have compiled a case history and possibly performed otoscopy. Audiometric assessment is another way of saying hearing test. The word audiometry is also used to describe the testing of hearing. When you perform audiometry you are finding the threshold of an individual’s hearing in comparison to the normal range. When you find the thresholds you write them on an audiogram. An audiogram is a chart of the individual’s hearing. There are many different types of hearing tests. Some words used to describe hearing tests are: subjective, objective, screening, diagnostic and electrophysiological. Electrophysiological tests look at how different parts of the hearing mechanism function and include Auditory Brainstem Testing (ABR), Auditory Cortical Testing (ACR), Otoacoustic Emissions (OAEs) and Electrocochleography (ECochG). These tests require special training to carry out and special skills to interpret the results. They are examples of objective tests, as the client does not tell you they have heard the sound. You will not be learning about these tests as they are beyond the scope of this course. You should, however, be aware of these tests. They are very useful tests and are often used when the client will not or cannot complete a hearing assessment. Diagnostic tests involve determining degree and type of hearing loss. This is compared to screening tests, which are used to quickly determine if there is a hearing loss that requires further attention. Subjective tests require the client’s cooperation. The client lets you know that they have heard the sound in some way. This topic is concerned with pure tone audiometry. Pure tone audiometry is the most common type of hearing test. It can be used for clients from about 3 years of age. Pure tone audiometry measures thresholds for pure tone sounds. Pure tone audiometry is a subjective test. That is, you are asking the client to indicate when they have heard a sound. To perform pure tone audiometry you need a machine called an audiometer. Audiometry should be performed in a suitable test environment. The test environment Audiometry is not valid if there is a great deal of background or ambient noise. Noise will affect hearing thresholds especially in the low frequencies. To reduce the effects of background noise you either have to find a very quiet spot or create a quiet environment. Most permanent audiometry clinics create a quiet environment by using a sound treated room. Why call it a sound treated room? Isn’t it a sound proof room? Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 6 Do you remember where there is no sound? The only place is in a vacuum. We can’t survive in a vacuum so there are no assessment rooms that are truly sound proof. The closest we can get to a sound proof room is an anechoic room. These are rooms that are covered in foam absorption material with a suspended floor. These rooms are used for experiments but are too expensive and bulky for most clinics. There are anechoic rooms in Chatswood NSW belonging to Australian Hearing which are sometimes open to the public. These are the quietest places in the Southern Hemisphere. Sound treated rooms vary in size. Some are big enough for only one person. Others are large enough to fit a desk and 3 - 4 people. They may be custom made or pre-fabricated. The major problems with sound treated rooms relate to the noise that is made by ventilation and lighting. Just because a clinic has a sound treated booth does not mean it automatically meets the standard for background noise. The levels of noise inside a booth need to be checked, particularly if the lighting and ventilation are changed. If the level of ambient noise does not meet the Standard you may need to do something about reducing the levels. Standard AS/NZS 1269.4 – 1998: Occupational Noise Management: Auditory Assessment published by Standards Australia provides the levels of ambient noise that are acceptable for audiometry. You will see different levels for different types earphones. You will need to use a sound level meter to check the levels of ambient noise in a test environment. If the room is large enough, audiometry may take place inside the booth. Therefore, the audiometer and clinician would be in the booth with the client. If the room is not large enough, only the client would be seated in the booth. Seating the client Whether or not the clinician is in the booth with the client it is best if you can see the client. Booths where the clinician sits outside usually have a window through which the clinician can watch the client. When the client and clinician both sit inside it is a little more difficult for the clinician to ‘hide’ what they are doing. Some clinicians prefer to seat the client so that they have their back to the audiometer. This is so the client is not able to see the audiometer and respond to something other than auditory stimuli. That is, the clinician does not want to cue the client by their actions that the sound is being presented. A compromise between this and staring directly at the client is to turn the client side on to the audiometer. You can still watch the client without feeling uncomfortable. Some clinicians suggest to the client that they close their eyes so that they can concentrate better. It is best to be able to see the client’s responses to the sounds because you are often able to see indications from the client when they are not sure they have heard the sound. You can then reassure the client that they did indeed hear the sound. The audiometer The machine needed to perform audiometry is the audiometer. It would be useful to have a diagram of the audiometer nearby for the next part of the learning guide. You might like to draw your own diagram of an audiometer and label the parts, including the frequency and decibel range. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 7 What does the audiometer do? The parts of the audiometer give you clues to answer this question. The frequency dial: The audiometer generates pure tones at various frequencies. Most audiometers will generate the following frequencies (in Hertz or cycles per second): 250, 500, 750, 1000, 1500 ,2000, 3000, 4000, 6000 and 8000. The decibel dial: This changes the intensity level of the frequencies in 5dB steps. The decibel scale is in Hearing Threshold Level. Most audiometers can change the level of sound from 0dBHTL to about 100dBHTL for air conduction testing. For bone conduction testing the upper limit is about 60dBHTL. Transducer: On most audiometers TDH39 or 49 earphones are used for air conduction testing and are labelled for the right ear and the left ear. Usually the earphones are coloured red and blue. Red is for the right ear and blue is for the left ear. These may be inside circumaural enclosures that will help with ambient noise levels. You may also be able to use E.A.R. 3A or 5A Insert earphones as an alternative. Bone conduction vibrator: This is used for bone conduction testing. An interrupter switch: This is the name often give to the switch or button used to present the sound. An output selector switch: This switch selects the right or left ear or the bone conductor. A patient response button: When pressed an indicator light shows the clinician that the client has heard the sound. What is the maximum output of the audiometer? Audiometers have a maximum level at which you can no longer increase the intensity. This will vary between audiometers and will depend on what frequency is being used and whether you are using the earphones or the bone conductor. Some audiometers have the facility to add an extra 20dB if you select it by pressing the relevant button. You need to be careful though to make sure you know whether the audiometer automatically shows the increase or not and whether you have turned it off. If the client does not respond to the maximum level then it is the convention in audiometry to indicate this level. You would do this by drawing the relevant symbol at that level with an arrow pointing down. The smaller audiometers have fewer features and are usually called screening audiometers. The larger audiometers with more features are called diagnostic audiometers. Diagnostic audiometers are often connected to other machines, e.g. a tape or CD player for speech testing, a computer for recording information. There are also automatic audiometers. They have an automatic testing protocol. These are often used in screening programs. This guide will focus on manual audiometry. Automatic audiometry has limited uses and does not allow the flexibility you need for testing most clients. So, what is the answer to the question: What does the audiometer do? The audiometer is a machine for determining hearing thresholds to pure tone sounds. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 8 You may be able to do many other types of assessments with an audiometer but this is the basic purpose of all audiometers. Hearing thresholds The word threshold means a starting point or beginning of awareness of a stimulus. When we talk about hearing threshold, we are talking about the point that there is an awareness of sound. What is a hearing threshold? In pure tone audiometry, threshold is the point at which a pure tone can just be heard 50%, half, of the time. In practice, a hearing threshold is the lowest intensity of a tone at which 2 out of 3 responses are observed. How is a hearing threshold observed? In pure tone audiometry the response to a sound is observed when the client indicates they hear it. This indication could be by raising the arm, hand or finger, tapping the table or by pressing a button. The client will respond to the sounds depending on the way you have instructed them. Instructing the client is extremely important. To achieve the best results possible you must instruct the client well. Instructing clients Your client must be clear about what is expected of them and what will happen. Your instructions should be clear and brief, letting the client know what to expect and how to respond. It is often useful to use gestures. The instructions must be understood. The client needs to understand: they are listening for very soft sounds they have to respond every time they hear the sound they will be hearing different tones the tones will be heard in one ear and then the other ear how to let you know they have heard the sound. Have you heard a clinician instructing the client? Keeping the above points in mind and what you have observed, how would you instruct the client? One way of instructing the client is to say something like: ‘You will be hearing a series of beeps and buzzes, first in the right ear and then in the left. As soon as you hear the sound, no matter how soft it is, let me know by pressing the button. Like this. (indicate how to press the button).’ The instructions should be kept simple and brief or your client might forget what you want them to do before they start. The instructions should not be vague. If you say, ‘Press the button when you think you hear a sound’, the client may be unclear about when to press the button. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 9 If you do not have a patient response button, you change the instructions so that the client is clear about what you want them to do. A gesture showing the client what to do is often helpful. This type of instruction is suitable for adult clients and older children. Most children can follow these instructions from about 8 years of age. Children under this age require special instructions. Play audiometry is suitable for children from about 3 years of age until about 8 years of age. Many children over 8 years of age will prefer to play a game to pressing the button so it is best to give them a choice. Play audiometry will be discussed later. Have you ever had a hearing test? If not arrange to have an assessment of your hearing. While you are having the assessment make a mental note of how you are instructed, what types of sounds you are listening to. Most of all you will come to realise that having an audiometric assessment involves a lot of concentration. Once you have instructed the client it is time to place the earphones. Placing the earphones Earphones are used to test air conduction hearing thresholds. Air conduction will be described very soon. Free field hearing testing is also used for specific reasons. Free field hearing testing is done without earphones. That is, the client sits in a sound treated room where a free field has been created and a sound is generated through a speaker. The client responds to this sound which is often a warble tone. A warble tone is based around a pure tone and includes the frequencies around it. For example, a warble tone at 1000Hz would include frequencies from 950 to 1050Hz. Warble tones avoid the problem of creating standing waves, i.e. dead spots. Primarily, free field testing is used for children who are less than 3 years of age. There are some specific speech tests that are conducted free field. It was, in the past, also used for testing aided thresholds. That is, hearing benefit obtained from hearing aids. Although some clinics may still have this facility, most have now switched to other methods of testing aided thresholds. You will learn more about this in the rehabilitation learning guide. You cannot use just any earphones for audiometric assessment. They must be a special kind of earphone. Australian and International standards set out what earphones can be used. Most audiometers have TDH 39 or TDH 49 headphones. You must use the earphones that belong to the machine that you are working with. That is, you must never swap earphones between machines. This is because it will effect the calibration of the audiometer. The only exception to this rule is if you would like to use E.A.R.-3A or E.A.R.-5A Insert Earphones. They are sometimes referred to as tube phones. Insert earphones may not be available in all clinics as they are not routinely supplied with an audiometer and are purchased separately. They have disposable foam tips that are inserted in the ear canal. These tips are attached to the insert earphones. Some audiometers will allow you to have more than one set of earphones attached at the same time and you can select which to use. More commonly, you would remove the headphones from the two jacks that are inserted Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 10 into the audiometer and replace them with the insert earphones. You will need to check whether there are any correction factors. Insert earphones have two advantages over the normal earphones. They are lighter with no band over the head. The second advantage is that they provide better results if there is some background noise. The disadvantage is that they are more invasive than normal earphones and you MUST perform otoscopy before inserting the foam tips. You would not use them if there were discharge in the ear canal or excessive wax present. For more information about the insert earphones you can look at the website of the company that developed them, Etymotic Research. The web address is www.etymotic.com. The special earphones needed for air conduction audiometry are called TDH-39 or TDH49. They may be used on their own or placed inside special cushions that are called circumaural or supra-aural cushions. They assist in making the test environment suitable for audiometry. That is, it is possible to have higher levels of ambient noise if you use circumaural cushions. Before putting on the earphones, ask the client to remove glasses, i.e. spectacles. You should also ask the client to remove earring/s if you suspect that they might dig in and cause pain or if they look like they could be bent out of shape by the pressure of the earphones. Make sure the client doesn’t forget to put them back on! The earphones must be put on carefully. That is, place the diaphragm of the earphones directly over the opening of the ear canal and the band sits across the top of the head. The diaphragm of the earphones looks like small circles in a larger circle. If the earphones are not placed directly over the opening of the ear canal, hearing thresholds could appear worse than they really are. This effect is most obvious at 6000Hz. Earphones can cause collapsed canals. This is where the canal is forced shut due to the pressure of the earphones. You can check for the possibility of collapsing canals during otoscopy. While looking at the pinna, if you push gently on the cartilage you can see if the ear canal opening seems to be closing. When you look in the ear canal the skin may seem very soft and loose, increasing the likelihood of the canals collapsing with pressure. If the canals collapse, hearing thresholds for air conduction will appear worse than they actually are. To avoid collapsing canals you can ask the client to hold the earphone gently against the pinna. The client’s arm may get tired so it is best to have the client lean their elbow on the arm of a chair or on the top of the desk. This is only necessary when you suspect the canals are collapsing. You could also use insert earphones if they are available. Now that the earphones are placed correctly on the client it is time to start the audiometric assessment. The earphones make it possible to perform air conduction audiometry. Air conduction Which ear do you test first? Do you think it matters which ear you test first? The convention is to start testing the right ear first unless there is a difference between the ears in which case you start with the better ear. Complete all frequencies for one ear and then switch to the other ear and test all frequencies. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 11 If the ears are the same, it does not matter which ear you start with. Some clinicians prefer to test both ears at each frequency before proceeding to the next frequency. But how do you know which ear is the better one before you do the test? You may not know, but it is likely that the client does. It often happens that the client will tell you or at least give you hints during the compiling of the history. If you prefer you can ask them, ‘Do you think your hearing is pretty much the same in both ears?’ At this stage, with the majority of your clients you have compiled the case history, performed otoscopy, the client is seated in the sound treated room with the earphones placed correctly and the audiometer is switched to the right ear. Now what? Now is the time for the clinician to sit down and start testing. The first frequency to test is 1000Hz. Most clients find this frequency fairly easy to hear. A common sequence is as follows, assuming both ears are likely to be approximately the same: 1. 2. 3. 4. 5. 6. 7. Right ear 1000Hz 2000Hz 4000Hz 8000Hz 1000Hz 500Hz 250HZ 8. 9. 10. 11. 12. 13. 14. Left ear 1000Hz 2000Hz 4000Hz 8000Hz 1000Hz 500Hz 250HZ These frequencies and 125Hz are the octave frequencies. Most clinicians do not test 125Hz unless there is a specific reason; e.g. client has a profound hearing loss. Sometimes the mid-octave frequencies are also tested. The rule for testing mid-octave frequencies is: you test mid-octave frequencies when there is a difference between octaves of 20dB or more. The mid-octave frequencies are 750Hz; 1500Hz; 3000Hz and 6000Hz. Some audiometers have extra frequencies above 8000Hz as well but you will need special headphones to test these frequencies. There is no reason not to test mid-octaves. Many clinicians prefer to include the testing of 3000Hz and 6000Hz. Many clinicians do not test at 125Hz and 250Hz. Depending on the purpose for the audiometric assessment various frequencies will be tested. In some cases you must test mid-octave frequencies particularly if the assessment is for work related purposes. In the above recommended sequence, 1000Hz has been rechecked. This is not always done. The reason for checking 1000Hz is to see if the client is consistent. That is, was the second response similar to the first response? If not, why not? Sometimes there is a training effect, i.e., the client is now aware of what is expected of them and responds better. In this case, take the better response and quickly recheck the other thresholds for improvement. If the client’s second response is significantly worse: Have they lost concentration?; Are they deliberately trying to make it appear that their hearing is worse?; Have they forgotten what you wanted them to do? Try encouraging the client to respond to the very soft sounds and to keep concentrating for a little longer. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 12 What have you just tested? Did you say you have tested the client’s hearing? That is partially true. You have tested one aspect of the client’s hearing. You have completed the air conduction component of pure tone audiometry. If you are doing a screening test, that may be all you need to do. Test-retest variability Test-retest variability is the minor differences that occur between tests. It is accepted that if there is 10dB difference between results then this is not a true difference and relates to test-retest variability. In other words, it is not considered to be a real difference until there is a variation of 15dB or more. But what does it all mean? Air conduction audiometry assesses the ability of the entire hearing mechanism to respond to pure tones. That is, the sound passes through the outer, middle and inner ear and up the neural pathways to the cortical region of the brain. If any part of the hearing mechanism is not operating properly the hearing will be affected. So when you do air conduction test and it shows a hearing loss you do not know where the site of lesion is. ‘Site of lesion’ is the terminology we use to describe the place of the breakdown of the hearing mechanism. Symmetry The hearing is considered to be the same in both ears if the results of the right ear and left ear at each frequency fall within 10dB of one another. That is, there is no test-retest variability. This is referred to as symmetrical. There may be a difference between the ears, i.e. asymmetry. This may mean that the responses come from the better ear. You may need to perform further testing before you can explain the hearing status of that client. This will be explained in the section on masking in the guide called Assessment B. The next step of the hearing assessment is bone conduction. The results from bone conduction testing when compared to air conduction testing will provide some information about site of lesion. Bone conduction What is bone conduction? Essentially, bone conduction is sound transmitted to the inner ear by the bones of the skull. To test for bone conduction you need a bone conduction vibrator, also called a bone conductor. This is placed on the mastoid process of the temporal bone, sometimes simply called the mastoid bone. That is, on the bony part behind the pinna. The bone conductor should not be placed on hair. On very rare occasions the bone conductor is placed somewhere other than the mastoid. The centre of the forehead is the most likely place. However, in Australia most clinicians will only perform bone conduction placed on the mastoid. For the bone conductor to work properly there must be a certain amount of pressure applied to the mastoid, that is why the band of the bone conductor is so springy. You must never over stretch the band so that there is little or no pressure against the head. The client may experience a little discomfort. You could say to the client: ‘This may feel a little tight, but it won’t be on for long. It has to be that way for the test.’ Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 13 It takes a lot of energy to drive the bone conductor so audiometers are unable to produce high intensity levels for bone conduction testing. Most audiometers cannot make the sound louder than about 70dBHTL. How does bone conduction work? Bone conduction is a very complicated process. When the bones of the skull vibrate there are at least three things happening. These are: 1. as the skull moves, the bones of the middle ear do not start moving immediately, i.e. they exhibit inertia, causing the stapes to move in and out of the oval window; 2. the bones of the skull distort and cause the cochlea to distort, this then causes activity that is the same as the activity that would have been created by air conducted sound; 3. the vibration of the skull causes the air in the ear canal (EAM) to vibrate, some of this vibration is passed on to the eardrum (TM). Theoretically the sound generated by the bone conductor bypasses the outer and middle ear. That is, the sound generated by the bone conductor goes directly to the inner ear. Responses obtained by using the bone conductor are considered to be for the inner ear and neural pathways. However, there are effects from the middle ear. The effect that you will come across when performing audiometry is called the Carhart’s notch. This effects the level of the bone conduction result at 2000Hz. Otherwise, you can think about bone conduction responses as being unchangeable by the outer and middle ear. And that the responses you achieve by performing bone conduction are a representation of the hearing level at the cochlear level. Which ear do you test with a bone conductor? In theory, the sound generated by the bone conductor reaches both cochleas. That is, when you test with a bone conductor it doesn’t matter which ear you put it behind, the sound will be transmitted to both sides. In practice, there may be a slight difference. However, you cannot say, that when you put the bone conductor behind the right ear you are only testing the right ear or when you put the bone conductor behind the left ear you are only testing the left ear. This is a very important point to remember for later when you learn about masking. Bone conduction is normally performed without covering the pinna. That is, when you test for bone conduction you remove the earphones you used for air conduction. So, if you were thinking of saving time and effort by placing the bone conductor and the earphones on at the same time - think again! There is a very good reason not to cover the ears when testing bone conduction. It is called the occlusion effect. During bone conduction testing, if the ear is covered, the occlusion effect increases the loudness of low frequency sounds i.e. 1000Hz or lower. One sequence you could follow to test bone conduction is as follows: 1. 2. 3. 4. Bone conduction 1000Hz 2000Hz 4000Hz 500Hz Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 14 If you tested other frequencies between 500Hz and 4000Hz for air conduction, you could also test them for bone conduction. Most audiometers do not produce bone conduction above 4000Hz. If bone conduction is available over 4000Hz you will have to check to see what calibration figures were used. If the audiometer has not been calibrated to the Australian standards then you can only use the figures as a guideline for yourself. Many clinicians do not test bone conduction at 250Hz because of the tactile nature of this sound. That is, it is often felt rather than heard so the information you get from doing bone conduction at 250Hz is treated with caution. In other words, you’re not always sure how useful the result is. Can bone conduction levels be worse than air conduction levels? The short answer to this question is no. However, it is possible that the bone conductor has not been placed on the mastoid very well. If this happens it is possible that the results may be effected. It may also occur if the client is not completely cooperative in the test situation and therefore would be considered an indicator that the client’s motivation is not to respond to threshold. It could also mean that the person has lost concentration. If the response is within 10dB then it is not considered a difference so you may just be showing a test-retest variability. Audiometric Weber The forehead setting for the bone conductor is sometimes used with a test called the Audiometric Weber. In this test the client is asked to point to which ear the sound is heard. The results are noted as right, left or central. Central means the client couldn’t hear the sound in only one ear and the sound seemed to be coming form somewhere else. It is usually only done at 1000Hz, 500Hz and 250Hz and a little above threshold as this is the easiest way to hear the sounds. It is not a common test now but was done quite routinely in the past. It is based on tuning fork tests that an ENT Specialist might use. It was used to help the clinician when there is some doubt about whether there is a middle ear component to the hearing loss. Carhart’s notch Carhart’s notch is where the bone conduction is affected at 2kHz by the condition of the middle ear. It is often seen when the client has otosclerosis, a common cause of conductive hearing loss in adults. If the client undergoes successful surgery, it is likely that the bone conduction at 2kHz will improve. Most of the time, though, you would not expect the bone conduction results to vary before and after surgery unless there has been an effect on the cochlea. When you have tested air and bone conduction you can start to describe the degree and type of hearing loss. But how did you actually get the results? The basic audiometric assessment method is called the Hughson-Westlake technique. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 15 The Hughson-Westlake technique When you are performing audiometric assessment you can use an ascending technique or a descending technique or a combination. The words ascending and descending mean going up and going down. When applied to audiometry, they relate to the clinician increasing the level of the sound or decreasing the level of the sound to determine the client’s hearing threshold. The Hughson-Westlake technique is the most common testing technique used. It is more correctly known as the modified Hughson-Westlake technique as the original method has been changed slightly. It is an ascending method and is sometimes referred to as the ‘up 5dB -down 10dB’ procedure. The first presentation is reasonably loud e.g. 60dBHTL. If the client responds, the intensity is reduced by 10dB until there is no response. It is then increased by 5dB until there is a response. The intensity is again reduced by 10dB until there is no response and then increased by 5dB until there is a response. If the initial sound is not responded to, increase the level of intensity by 5dB until the client responds. Sometimes starting at 60dBHTL is too loud. If the client is likely to have normal or near normal hearing it would be better to start at 30dBHTL. Occasionally it is best to start at 0dB and increase from there. The threshold is determined when there are 2 out of 3 responses. Only the responses on the ascending series are taken into account, which is why it is called an ascending technique. For example, in the right ear at 1000Hz: 60dBHTL 50dBHTL 40dBHTL 45dBHTL 35dBHTL 40dBHTL 30dBHTL 35dBHTL 40dBHTL 30dBHTL 35dBHTL 40dBHTL response response no response response no response response no response no response response no response no response response The threshold of hearing at 1000Hz in the right ear is 40dBHTL. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 1st 2nd 3rd 3064-9/HLSP Audiometry – Assessment A V1 16 Summary 1. Seat the client in the sound treated room. 2. Instruct the client clearly. 3. Place the earphones/bone conductor. 4. Start at 1kHz at a level that will easily be heard, try 60dBHTL or 30dBHTL in the right ear or the better ear. 5. If the client responds decrease by 10dB. 6. If the client does not respond increase the sound by 5dB. 7. Obtain 2 out of 3 responses at the same level in an ascending manner. 8. After 1kHz is finished, test 2kHz, 4kHz, 8kHz, recheck 1kHz then do 500Hz and 250Hz. If there is a difference between octaves of more than 20dB test the inter-octave frequencies. 9. Repeat for the other ear. 10. Repeat for bone conduction. dBHTL Do you remember the definition of dBHTL? Decibels Hearing Threshold Level is based on the average hearing level of a large group of young adults with no history of hearing problems where 0dBHTL is the average hearing threshold. It is very important for you to fully understand what this means. If you have forgotten or can’t explain it, now is the time to go back and review this concept. Appropriate techniques for different clients The Hughson-Westlake is not the only technique used. However all audiometric assessment methods use an ascending or descending technique or a combination of the two. Many clinicians prefer an ascending technique in which the starting level is very soft, 0dBHTL is appropriate for clients with normal or near normal hearing. The level is increased until there is a response and then follows the ‘down 10, up 5’ process of the Hughson-Westlake. Many clinicians feel this encourages the client to respond at very soft levels and is a quicker assessment technique. This may be suitable for a client who is not motivated to respond to soft levels of sound. One combination method is sometimes called bracketing. Initially the clinician increases the sound until the client responds. A louder sound is then presented and the sound is decreased until the client stops responding. A number of series are used to establish the softest intensity level at which the client responds to 2 out of 3 presentations. There are techniques where the client controls the level of presentation. One of these is called Bekesy audiometry. This was a common technique until the 1980s. It is an automatic technique. The client keeps their finger on a response button while they hear the Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 17 sound and remove it as soon as the sound stops. There are now other automatic audiometers that you may use in certain clinics. Automatic audiometers do not offer the flexibility of adjusting your testing method to suit the client. Screening tests are often used to check large populations quickly to highlight problems that should be followed up. For example, children in schools may be screened. The clinician would decide on the pass/fail criteria. Usually, children would be expected to respond at 20dBHTL at 500Hz, 1000Hz, 2000Hz and 4000Hz for both ears. In this type of screening test only these sounds would be presented. Children who do not respond at these levels would then be assessed more thoroughly. Take the opportunity whenever you can to observe different methods that clinicians use and try to find out why they prefer those methods. With experience you also will respond to different clients to help them complete the audiometric assessment. The pattern of presentations So far we have talked about the sequence of presenting the frequencies and the intensity of the pure tones you want to test. You also need to know how to present the sounds so that the client does not know when to expect to hear them. That is, you must present the sounds randomly or the client may respond to the patterning of your presentations rather than hearing the sound. This is particularly important when testing children. When you perform a hearing assessment you want your results to be valid. A valid response is one which measures what it intends to measure. When you are testing hearing you want to be able to measure the client’s hearing, not their ability to guess when you are about to present the sound. When you begin clinical practice you might find it helpful to count to yourself between presentations. For example, present 1st sound, count to 5 present 2nd sound, count to 9 present 3rd sound, count to 6 present 4th sound, count to 3, etc. Another way of saying this is, you must vary the inter-stimulus interval randomly. One mistake that is often made is that the clinician presents the sounds too quickly, i.e., they do not allow enough of a break between the stimuli. This often confuses the client and leads to false positive responses and false negative responses. A false positive response occurs when the client indicated they have heard a sound when none was presented. A false negative response occurs when the client does not indicate they have heard a sound even though they have. If you present the sounds too quickly the client may not respond because they think it is the same sound. Or they may keep responding because they are anxious they will miss a sound. Some clients say they think they are hearing an echo. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 18 It is better to allow slightly longer inter-stimuli intervals. If the client does start to respond haphazardly, slow down. You may even need to stop, give the client a quick break and reinstruct. So you can see it does not save time to present the sounds quickly. It often takes a lot longer. If you take too long between presentations, however, the client may begin to think there is something wrong. Clinics rarely have unlimited time for a hearing assessment so you will have to learn to find the correct balance between being too quick and being too slow. Length of presentation The length of presentation should be between 1 and 2 seconds. If you say ‘one thousand and one’ to yourself while holding the interrupter, the tone will be on for long enough for the client to hear. If the tone is too short, the sound will have to be louder for the client to hear it. Keeping the tone on longer than about 2 seconds makes no difference to hearing the tone. Some clients have difficulty detecting the pure tone because of tinnitus. That is, their own head noises make it difficult for them to know when the tone has been presented. For these clients, if you present the tone as a pulsed tone it will help them. A pulsed tone will sound like a ‘beep beep’ presentation and each beep should be about 1 second in duration. Some audiometers have a pulsed setting that you can use. Some clinicians use a warble tone – this is acceptable if the tinnitus is so problematic that the client cannot do the test any other way. If you do vary the test technique it is worthwhile to make a note of what you did and why it was done. For example: ‘Mr X had trouble with 4kHz because of tinnitus so I used beep beep presentation’. Dealing with clients who can’t / won’t co-operate One of the aims of performing audiometry is to achieve reliable responses. A reliable response is one that can be repeated. So a reliable audiogram is one that can be repeated at any time by any suitably trained clinician using calibrated equipment anywhere in the world. When you first meet your client you assume that they are willing and motivated to do their best. You also presume they are able to maintain the level of concentration necessary to complete the test. These client related conditions will assist you to achieve a reliable audiogram. You should start every audiometric assessment with the attitude that your client will participate fully with you. It is not common that your client is not motivated to do the best they can. If you feel the client should be doing better, give them the benefit of the doubt, they may not have understood exactly what you wanted them to do. Try reinstructing the client. Some clients genuinely believe that you cannot possibly want them to respond to the very soft sounds so you may need to explain the procedure to them. Audiometry is affected by the client’s ability to concentrate. The assumption is that clients are able to maintain the level of concentration necessary to complete the test. If the client Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 19 is not well or is unable to maintain the level of concentration needed then your results will be affected. You should make a comment in your file notes. For example: ‘Mrs T told me she was unwell today and could not concentrate well. Will book her in for a quick retest in 2 weeks time. I have asked her to cancel the appointment if she is still unwell and make another when she is feeling better’. If you feel that it is unlikely that the client will be able to concentrate for long enough you will have to decide what is most important. Usually the frequencies that are tested first in this situation are 1kHz and 4kHz. You may have to do a test over a number of appointments to get a full audiogram. It does not happen very often but occasionally you will be required to test a client who is not motivated to respond to the softest sounds they can hear. You may get some indication from the case history. For example, they might tell you about the extreme difficulty they are having at home because they do not hear well yet have no problem responding even when you talk to them from behind their back. These clients usually have a motivation. Some clients hope to receive workers compensation. Some clients simply want a little attention from their families. Whatever the motivation, these clients need special handling. With experience, you will get a general impression of overall impairment before you start the assessment. A severely or profoundly hearing impaired person who has no hearing aid will not respond without being able to see you. A client who answers questions appropriately when you are standing behind them, i.e., they can’t see your face, and you are using a soft voice is unlikely to have more than a mild hearing loss. With many of these clients an ascending audiometric technique is more appropriate. Some will simply respond to extra encouragement and kindness. Speech testing may also help you in this situation. You will learn a lot by watching experienced clinicians dealing with these clients. You will have to make a decision about the reliability of the responses. You can only write the best response the client has given on the audiogram. If the client would not or could not cooperate you cannot say that you know the client’s hearing is better and therefore, note the threshold as better on the audiogram. What you can do is write the best responses on the audiogram and write something e.g.: ‘client said he was doing the best he could’. Be extremely careful what you write, it is best to describe behaviour or write comments that the client made. You must never make derogatory remarks or personal comments about clients e.g.: ‘Mr X was being a real pain today’, ‘client acted stupid’ etc. If you are concerned about testing clients you can ask your supervisor if they would like to complete the testing. Certain tests do not require the client’s cooperation. These are called objective tests because the client does not tell you they have heard the sound. Electrophysiological tests are objective tests. These include Auditory Brainstem Testing (ABR), Auditory Cortical Testing (ACR), Oto-acoustic Emissions (OAEs) and Electrocochleography (ECoG). These tests require special training to carry out and special skills to interpret the results. You will not be learning about these tests as they are beyond the scope of this course. However, you may consider referring clients to a clinic that performs these tests particularly if there is a legal reason for obtaining an accurate audiogram. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 20 Play audiometry When testing children, keep in mind that you may not be able to keep their interest for long enough to complete the audiogram unless you incorporate play into the assessment. You would tell the child at the beginning that you want them to play a listening game. Show them what you want them to do, e.g., put a peg in a bucket, a ring on a pole, and ‘shape’ the response. That is, train the child to do the activity to a sound before putting on the earphones. Then work as quickly as possible to get the results without working so quickly that the child gets confused. When working with children you adjust your testing technique to obtain the most important information first. A typical sequence for working with children is as follows: 1. 3. 5. 7. 9. 11. Air conduction: Right ear 1000Hz 4000Hz 2000Hz 500Hz Bone conduction 1000Hz 2000Hz 2. 4. 6. 8. Air conduction: Left ear 1000Hz 4000Hz 2000Hz 500Hz 10. 12. 4000Hz 500Hz This sort of technique is appropriate for children from about 2 ½ years of age to about 8 years of age. The most variable age group is children aged 2 ½ to 3 ½ years. You can test some in this age group successfully but not all. It is not possible to predict which child will work with you and which will not. Some children will do very well until you try to put the earphones on and will object to them. Older children may not like to play ‘baby games’ so you may need to find something more appealing to the older age groups. A child of 7 may like to draw ticks on a page or use self inking stamps to make a pattern. A child of 8 may like to feel grown up and press the button like an adult. Children are usually very happy to tell you what they would like to do. However, you need to be cautious about asking the child a yes/no question when a no answer is unacceptable. For example, ‘Will we go in here?’ (i.e. to the test booth). If the child says no, what are you going to do? You could ask ‘Will we play the peg game or the tower game?’, i.e. offer them alternatives. It is better to allocate a little extra time for testing young children so that you have sufficient time to get to know them and to instruct them. It is common for a young child to forget what they have to do during a test so you may need to reinstruct them. Tactile responses Some sounds generated by the audiometer are sufficiently loud to produce a perceptible vibration. That is, the client responds to a sound not because they heard it but because they felt it. Another way of saying this is that the client is responding to tactile stimuli. This happens most commonly to low frequency sounds generated by the bone conductor. Many clinicians do not test for bone conduction below 500Hz because of the likelihood of this happening. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 21 If a client responds only to air and bone conducted sound below 1000Hz at the maximum levels of the audiometer it is possible that they are responding to tactile stimuli. Some clients are unable to tell you whether they heard the sound or felt it. However, you should ask. If the client informs you that they felt it, you can report that the responses were ‘tactile’. These responses are still valid for the audiometric assessment and, therefore, you can note them on the audiogram. The following are likely to be tactile responses: Air conduction: Bone conduction: 250Hz at 90dBHTL 500HZ at 100dBHTL 1000Hz at 120dBHTL 250Hz at 40dBHTL 500Hz at 70dBHTL. Do not think that every time you get these responses they are tactile. They may be auditory responses, however, if these are the only results you get, you should ask the client: ‘Did you hear those sounds or did you feel them?’ The audiogram The audiogram is the chart of the client’s hearing. As you test them you will write down the results. The audiogram looks like this: PURE TONE AUDIOGRAM HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) 250 500 1000 2000 4000 8000 -10 -10 0 0 10 10 20 20 30 30 40 40 50 50 60 60 70 70 80 80 90 90 100 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O Masked Left ] Right [ No response Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 22 You can see the octave frequencies are written across the top. The mid-octaves are written on the lines between them. On the side is the intensity level in decibels Hearing Threshold Level. The lines are in 10dB steps so if a response is obtained at 45dBHTL it would be written between the 40 and 50 lines. The only symbols in audiometry that are internationally agreed on are for unmasked air conduction. The ‘o’ is used for the right ear and the ‘x’ is for the left ear. Unmasked bone conduction results may be shown as ‘ ’ or ‘<’ for the bone conductor placed on the right mastoid or ‘>’for the bone conductor placed on the left mastoid. When the maximum output of the audiometer has been reached and the client has still not indicated they have heard the sound an arrow is added to the symbol, e.g., . By convention the results for the right ear are joined by an unbroken line and the left ear by a dashed line. These symbols are for unmasked audiometry, masking will be discussed in another learning guide and is necessary when there is a difference between the ears. Whatever symbols you use, they should be written on the audiogram. Most audiograms have the symbols printed on them along with a space for the date, client’s name, audiometer used and clinician’s name. Type and degree of hearing loss The audiogram will give you the information to describe the hearing in terms of degree and type. The type of hearing loss requires you to have done both air and bone conduction testing. The degree of hearing loss is described as mild, moderate, severe or profound. If responses are recorded at less than 25dBHTL the hearing is within the normal range. Mild hearing loss 25 to 45dBHTL Moderate hearing loss 50 to 70dBHTL Severe hearing loss 75 to 90dBHTL Profound hearing loss more than 90dBHTL. The most common way to describe a hearing loss is to look at the results between 500Hz and 4000Hz. This is not a strict guideline, though, as there are many situations that the levels of the other frequencies are very important. It often happens that the hearing loss is in more than one region. When this happens you can join the degree of loss. For example, mild-moderate, severe - profound etc. The type of hearing loss is described as sensorineural, conductive or mixed. These terms define the site of lesion, i.e., where the breakdown in hearing occurs. In a conductive hearing loss, the breakdown in hearing occurs in the outer or middle ear. In a sensorineural hearing loss the breakdown in hearing occurs in the cochlea or beyond. A mixed hearing loss involves a combination of conductive and sensorineural impairment. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 23 On the audiogram: a conductive hearing loss is shown by the bone conduction within the normal range and the air conduction outside of the normal range a sensorineural hearing loss is shown by the bone conduction and the air conduction being equal and outside of the normal range a mixed hearing loss is shown by the bone conduction and the air conduction being outside of the normal range but the bone conduction results are better than the air conduction, i.e. there is an air-bone gap. Air and bone conduction are considered to be equal if they are within 10dB of one another. In other words, if there is a gap between the air conduction and the bone conduction of 15dB or more it is considered that there is an air-bone gap. Bone conduction should never be worse than air conduction. If it is, check that you have placed the bone conductor on properly. There is another type of hearing loss that the audiogram cannot define. The audiogram can only provide information about the peripheral hearing mechanism, i.e., the outer, middle and inner ear. The audiogram cannot provide information about a processing disorder or a problem at the cortical level. Clients with a processing disorder display communication difficulties beyond what is expected for their degree of hearing. It is often related to a problem with the transmission of the sound from the cochlea to the brain. If you suspect that the client has a processing disorder you will need to refer your client to a clinic that performs the relevant assessment. Other descriptions are used for the audiogram. Sometimes, the clinician will include a comment about the slope of the audiogram. It is common for the audiogram to gently slope from the low frequencies to the high frequencies and so this is not usually commented on. A comment is usual if the audiogram is upwardly sloping or if it is steeply sloping. You can describe each ear separately or it the ears are the same you can describe them together. Monaural means one ear and binaural means two ears. Unilateral means one sided and bilateral means two sided. If the ears are different you can define the hearing loss as asymmetrical or if they are the same you can say the hearing loss is symmetrical. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 24 The 3FAHL The three frequency average hearing loss (3FAHL) is often used to describe hearing loss. To calculate the 3FAHL, add the decibel levels at 500 1k 2k for one ear and then divide by 3. The figure can be rounded off to the nearest multiple of 5. For example, the responses for the right ear are: 500Hz 30dBHTL 1000Hz 40dBHTL 2000Hz 55dBHTL 30+40+55=125 125 divided by 3 = 41.66 rounded off to 40dBHTL The 3FAHL may help you to decide the degree of hearing loss. The 3FAHL is also used in speech audiometry so it is worthwhile to take some time to practice looking at some example audiograms and working out the 3FAHL. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 25 Some examples of audiograms with their descriptions AUDIOGRAM 1 AUDIOGRAM 2 PURE TONE AUDIOGRAM PURE TONE AUDIOGRAM 500 1000 2000 4000 -10 0 10 20 250 8000 0 10 20 30 30 40 40 50 50 60 60 70 70 80 80 90 90 100 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O Masked Left ] Right [ No response HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) 250 -10 500 1000 2000 4000 8000 -10 -10 0 0 10 20 30 10 20 30 40 40 50 50 60 60 70 70 80 80 90 90 100 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O Masked Left ] Right [ No response Audiogram 1: Pure tone audiometry shows hearing is within the normal range for both ears. In this audiogram bone conduction testing has been done but many clinicians would not do it. It depends on why the test is done whether you would do the bone conduction testing. It is more common to test for bone conduction if the doctor is worried about middle ear problems. If this test were done for screening purposes then you would probably not do bone conduction. Audiogram 2: Pure tone audiometry shows hearing is within normal limits but there is an air-bone gap. In this circumstance hearing is within normal limits but there is an effect on the hearing by something in the outer or middle ear. That is, there is a conductive element. We do not know if both ears are affected as the bone conduction result may relate to both ears or only the better one. Further testing is needed, i.e. masking. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 26 PURE TONE AUDIOGRAM 500 1000 2000 4000 PURE TONE AUDIOGRAM 8000 -10 0 10 10 20 20 30 40 50 250 -10 0 30 40 50 60 60 70 70 80 80 90 90 100 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O Masked Left ] Right [ No response HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) 250 500 1000 4000 8000 -10 0 0 10 10 20 20 30 30 40 50 40 50 60 70 60 70 80 80 90 90 100 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O NB No masking was attempted as child was too young AUDIOGRAM 3 2000 -10 Masked Left ] Right [ No response AUDIOGRAM 4 Audiogram 3: Audiogram shows a mild hearing loss in both ears, conductive in nature in at least one ear but probably both. When you learn about masking you would perform masking for this client or make a comment about why masking could not be done. Audiogram 4: Hearing test today shows a mild-moderate sensorineural hearing loss. Remember if air and bone conduction results are within 10dB of one another then it is considered that there is no air-bone gap. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 27 PURE TONE AUDIOGRAM PURE TONE AUDIOGRAM 500 1000 2000 4000 250 8000 -10 -10 0 0 10 10 20 20 30 30 40 40 50 50 60 60 70 70 80 80 90 100 90 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O Masked Left ] Right [ No response HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) 250 500 1000 2000 4000 8000 -10 -10 0 0 10 10 20 20 30 30 40 40 50 50 60 60 70 70 80 80 90 100 90 100 110 120 250 110 120 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O AUDIOGRAM 5 Masked Left ] Right [ No response AUDIOGRAM 6 Audiogram 5: Audiometric assessment shows a severe to profound hearing loss. This audiogram cannot be defined as sensorineural or mixed because there is insufficient information. This is because there were no responses to bone conduction. We do know that this is not a conductive hearing loss because the definition of a conductive loss is that the bone conduction is within the normal range but the air conduction is out of the normal range. Audiogram 6: Mr B suffers from a profound hearing loss. This is called a corner audiogram. It is possible these are tactile responses. In this case bone conduction has not been attempted. The most likely explanation for this is that this is a repeat audiogram to check that the hearing loss is stable and previous testing has shown no response to bone conduction. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 28 PURE TONE AUDIOGRAM 500 1000 2000 4000 8000 -10 250 -10 0 0 10 10 20 20 30 30 40 40 50 50 60 60 70 70 80 80 90 90 100 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O Masked Left ] Right [ No response AUDIOGRAM 7 HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) 250 PURE TONE AUDIOGRAM 500 1000 2000 4000 8000 -10 -10 0 0 10 10 20 30 40 50 60 70 20 30 40 50 60 70 80 80 90 90 100 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O Masked Left ] Right [ No response AUDIOGRAM 8 Audiogram 7: Audiometry shows hearing is within normal limits to 1kHz with a steeply sloping, apparently sensorineural, moderate to severe loss, above this. The words ‘apparently sensorineural’ are used because there is limited information to say this at this stage. This is because there was no response to bone conduction at 2kHz and 4kHz. The position of the symbol showing that there is no response has been placed at 70dBHTL. This shows that the maximum output of the audiometer was at this level. When we talk about audiograms it is customary to describe them based on the results between 500 and 4kHz. Audiogram 8: Hearing test shows a moderate hearing loss in the low frequencies sloping upwards to a mild loss in the high frequencies, bilaterally. The hearing loss is conductive in nature in at least one ear. Further testing is required, however, masking was not attempted as P is only 4 years of age and had become inattentive. Masking is often possible in children if you can maintain their attention span. Some children become confused with masking and cannot manage. In this case you could write something like ‘Masking attempted but unsuccessful’ A hearing loss that is purely conductive cannot be greater than a moderate loss or putting it another way, a maximum conductive loss is around 70dBHTL. When the hearing levels from both ears are within 10dB of one another at a particular frequency then they are considered to be symmetrical. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 29 The audiogram can provide clues about the cause of the hearing loss. PURE TONE AUDIOGRAM 500 1000 2000 4000 8000 -10 0 10 250 -10 0 10 20 30 20 30 40 40 50 50 60 60 70 70 80 80 90 90 100 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O Masked Left ] Right [ No response AUDIOGRAM 9 HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) 250 PURE TONE AUDIOGRAM 500 1000 2000 4000 8000 -10 -10 0 10 20 0 10 20 30 30 40 40 50 60 70 50 60 70 80 80 90 90 100 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O Masked Left ] Right [ No response AUDIOGRAM 10 Audiogram 9: Audiogram shows hearing is within normal limits except at 3kHz and 4kHz which show a mild sensorineural loss in a ‘notch’ pattern, consistent with the effects of noise. Audiometrists cannot make medical diagnoses so you can’t say ‘the hearing loss was caused by noise’ but you can say, ‘the hearing loss is consistent with the effects of noise’ as a ‘notch’ is unlikely to be caused by anything other than noise. You would also expect that the client’s history would show excessive noise exposure. A Noise Induced Hearing Loss (NIHL) will often show a ‘notch’ pattern. After many years of noise exposure the notch will start to flatten out and the audiogram will be similar to that of presbycusis. Audiogram 10: Audiogram shows a mild-moderate high frequency hearing loss of a sensorineural nature. Presbycusis is the name given to hearing loss caused by aging. The typical configuration or shape, is a sloping high frequency sensorineural hearing loss. This is also the most common pattern for all hearing loss. That is, most people who have a hearing impairment will have a high frequency loss. However, you CANNOT say ‘This hearing loss is caused by presbycusis’ because only a doctor can say that. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 30 PURE TONE AUDIOGRAM HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) 250 500 1000 2000 4000 8000 -10 -10 0 0 10 10 20 20 30 40 50 30 40 50 60 70 60 70 80 80 90 90 100 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O Masked Left ] Right [ No response AUDIOGRAM 11 Audiogram 11: Audiogram shows a bilateral mild-moderate hearing loss. It is conductive in nature in at least one ear. Further testing is required. Conductive hearing loss is caused by many conditions of the outer and middle ear. The most common causes of conductive hearing loss are otitis media (in children) and otosclerosis (in adults). Conductive hearing loss shows an air-bone gap on the audiogram. You often see an effect called the Carhart’s notch. This is where the bone conduction is affected at 2kHz by the condition of the middle ear. If the client undergoes successful surgery, it is likely that the bone conduction at 2kHz will improve. It is usual for a conductive hearing loss to affect the low frequencies more than the high frequencies. This client requires masking, until you know how to do it yourself you would ask your supervisor to take over the testing. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 31 The audiogram may alert the clinician to problems in the testing procedure. PURE TONE AUDIOGRAM PURE TONE AUDIOGRAM 500 1000 2000 4000 8000 -10 250 -10 0 0 10 10 20 20 30 30 40 40 50 50 60 60 70 70 80 80 90 90 100 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O Masked Left ] Right [ No response AUDIOGRAM 12 HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) HEARING LEVEL IN DECIBELS (I.S.O. STANDARD) 250 500 1000 2000 4000 8000 -10 -10 0 10 20 0 10 30 40 20 30 40 50 50 60 60 70 70 80 80 90 90 100 100 110 110 120 120 250 500 1000 2000 4000 8000 FREQUENCY IN HERTZ AIR: Left X Masked Bone: Unmasked Right O Masked Left ] Right [ No response AUDIOGRAM 13 Audiogram 12: If the earphones are causing collapsing canals the audiogram will show an air-bone gap in the high frequencies. It is unusual to have an air-bone gap in the high frequencies so you must always check for collapsing canals. To correct this problem, place the earphones correctly or ask the client to hold the earphones against their ears without too much force. If you have access to E.A.R. insert earphones you could try using them. Audiogram 13: Incorrect placement of the earphones has the greatest effect in the high frequencies, especially at 6kHz. It is advisable to quickly recheck thresholds in the highs after repositioning the earphones. If the earphones are placed incorrectly the thresholds in the high frequencies will improve after repositioning the earphones. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 32 3064-9/HLSP Audiometry – Assessment A V1 Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 33 SPEECH AUDIOMETRY After completing pure tone audiometry you may proceed with speech audiometry. You would not perform speech audiometry for every client you see. It is rare to include speech audiometry in a screening test. If the client comes from a non-English speaking background it may not be appropriate to perform speech audiometry. When carrying out speech audiometry the speech may be presented live voice or by using a recording. A live voice test is a speech test where the clinician presents the speech stimuli through the microphone of the audiometer. Recorded speech tests are available on audio cassette or CD. There are some recorded speech tests materials available using different varieties of English speakers and if you have a choice you should use the variety used by the client. That is, recordings using Australian speakers are preferable for Australian clients than recordings made using other accents. There are advantages and disadvantages in both kinds of presentations. Live voice tests can be conducted using any speech test material, and therefore, there is a great deal of flexibility. However, they cannot be used to compare results on one day to another or from one clinician to another. It is very difficult for the clinician to maintain the level of presentation with absolute accuracy when presenting live voice but this is obviously no problem with a recording. Speech audiometry can be presented monaurally or binaurally i.e., to one ear or both ears. Many clinicians feel that speech has greater applicability in determining the effect of a hearing impairment, as communication through speech is the major function of hearing. It is possible for two clients to have the same audiogram but have very different abilities to use the information they receive. If you determine handicap by the pure tone audiogram both would have the same degree of disability. The difficulty with using this approach is that there are many variables that affect the ability of an individual in a speech test. These include the experience, education and culture of the client. If the client is unfamiliar with the speech material used then they will not score as well. In comparison, the variables in pure tone audiometry can be controlled so one person’s audiogram can be directly compared to another’s. Speech Audiometry is used for a variety of reasons. It may be used: 1. To check the validity of pure tone audiometry. 2. To determine speech discrimination. 3. To establish rehabilitation needs. 4. Diagnostically. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 34 Checking the validity of the pure tone audiogram There is a strong relationship between the 3FAHL and the SRT and therefore can be used to check if the client is giving reliable responses The SRT is the Speech Reception Threshold. The SRT is the intensity at which simple speech material, usually spondees, can be detected 50% of the time. Spondees are word with two syllables that have equal stress on each of the syllables, e.g., fruitcake, meatball, childcare etc. The spondees are usually presented live voice. Determining speech discrimination When there is a hearing loss there is a breakdown in the hearing mechanism. When the client has a conductive loss it is usual that they are still able to discriminate speech very well but they need extra volume to do so. That is, the breakdown affects how loudly speech is heard but not how clearly. However, when the client has a sensorineural hearing loss, the clarity of speech is affected so that no matter how loud the speech is heard it will still not be clear. To determine how well a client can discriminate speech, speech discrimination tests are performed at the level that will produce the best results. The intensity level at which maximum speech discrimination will occur is not easy to predict. The rule of thumb is that the intensity level at which speech is best discriminated is usually 30 - 40dB above 3FAHL. Speaking to the client through the earphones will help to establish the level at which the client will hear speech best. This level is usually about 10dB above the most comfortable level (MCL). There is no one speech test that is used by all clinicians to determine speech discrimination. Most clinicians will use monosyllables, i.e. single syllable words. There are lists of words that have been devised for this purpose. Some clinicians prefer to use a number of short lists to compare scores across a range of intensity levels. This will provide the clinician with a better understanding of the client’s abilities and disability. Many clients will expect an amplification device to solve their communication difficulties. There is no hearing aid that will repair the damage that caused the hearing loss. If the client has poor speech discrimination their expectations may be unrealistic. Knowing the client’s ability to discriminate speech will assist the clinician to explain to the client the benefits that can be realistically expected from an amplification device. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 35 Establishing rehabilitation needs The aim in rehabilitation of clients with a hearing impairment is to reduce their communication difficulties. The majority of clients with a hearing impairment will hope to improve their ability to understand speech. Therefore, speech tests are used to determine the types of problems experienced. Many clients experience difficulties in background noise. It is possible to perform speech tests in noise but there is no standard procedure used across Australia. There are tests available if you want to do this. If you want to demonstrate tactics or show the benefit of an amplification device you can use a radio for background noise or use a recording of ‘cocktail party noise’. Speech tests may also assist in determining the level at which the client experiences discomfort. The uncomfortable loudness (UCL) level should be kept in mind when selecting an amplification device. Diagnostically Speech tests are often used to determine the site of lesion of the hearing impairment. Speech tests are particularly effective in diagnosing central impairments. A performance intensity (PI) function can be plotted for diagnostic reasons. The discrimination score achieved at a number of different intensity levels are plotted on a graph. If the speech discrimination reaches a maximum point and then gets worse as the intensity is increased this shows rollover. If rollover is observed the client must be referred to a doctor or an audiologist for full diagnostic audiometric assessment. NB: Recording the intensity level of speech. Speech is a broad band signal and is often recorded in dBSPL. Audiometers vary in the relationship between the intensity displayed and the level of speech. You will need to check the manual for your audiometer to know what this relationship is. Many audiometers have a 20dB correction. That is, at 0dB on the audiometer the speech is presented at 20dBSPL. You must write the correct level on your file. However, you must check with the clinic you are working in as to the procedures followed. Conveying results to clients All clients are entitled to understand the results of their audiometric assessment. They must be able to understand what you are telling them so you should avoid the use of specialised words, jargon, that won’t mean anything to the client. Most clinicians prefer to explain their own results but this depends on where you work and the purpose of the hearing test. For example, if you work for a doctor they may prefer to explain the results themselves. If nothing else you should at least give the client an encouraging comment like: ‘You did that test really well. The doctor will explain the results to you’. Many clients ask what percentage hearing loss they have. Percentages are relevant in workers compensation but do not convey much meaning. What would it mean to you if I said you had a 10% hearing loss? Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 36 It is more meaningful to describe hearing loss in terms of the types of hearing problems a client will have and relate the results to the history. At the end of the explanation of the results you should tell the client what action needs to be taken. For example, to a client with a mild-moderate, high frequency sensorineural hearing loss that is the same in both ears. The client has already seen an Ear Nose and Throat Specialist who has said there is no medical treatment and the otoscopy was clear. During the history the client told you they are seeking your advice about hearing aids. ‘This is the chart of your hearing. We call it an audiogram. Across the top of the audiogram is the frequency of the sounds you were listening to. The low pitch ones are on this side and the high pitch ones are on this side. This isn’t the full range of human hearing but these are the most important frequencies for understanding speech. The full range goes from 20 cycles per second or Hertz up to 20,000 cycles per second. Down the side of the audiogram is how loud the sounds have to be for you to just hear them. The further down the page the louder the sounds had to be. The circles are your right ear and the crosses are your left and you can see they are about the same. This half box is called bone conduction. That was that vibrator that was sitting behind your ear. The bone conduction results tells us where the hearing problem is. The results are about the same as the others so we know that there is nothing in your ear canal or in your middle ear causing the hearing problem. This means that the doctor can’t fix your hearing. Your problem is called a sensorineural hearing loss which means there is some damage in the inner ear. If your hearing was in the normal range all the circles and crosses would be above the line at 25dB. Your hearing is fairly close to normal in the low frequencies but gets worse in the higher frequencies. The low frequencies give us a lot of the volume for speech but the high frequencies give us a lot of information for the clarity of speech. So you can hear that someone is speaking but you can’t always make out what they are saying. Especially when you’re at the club and there’s a lot of noise or you can’t see the person’s face. Hearing aids would definitely help you.’ This is just one way of explaining results to clients. It is not suitable for every client. Some clients do not need as much explanation and some need more. Clients do not remember everything you say to them so giving written explanations is helpful. You can prepare general information beforehand and highlight relevant parts. Information giving is an ongoing process and you should be prepared to answer client’s questions at any time. You may also recommend that clients get more information from self help groups. These groups often have information brochures to help people understand hearing loss. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 37 Referring clients An audiometrist cannot refer clients in a medical sense. When we talk about referral in audiometry we are simply talking about asking the client to see someone else. There are many people who work with the audiometrist. These include: Audiologists the General Practitioner - GP the Ear Nose and Throat Specialist (ENT) Paediatricians Neurosurgeons Teachers Occupational Health and Safety Practitioners Rehabilitation Counsellors Occupational Therapists Speech Pathologists Self help Groups. The majority of clients will have been asked to see you for an assessment for a variety of reasons that can be classified as follows: Medical Rehabilitation Educational. You will ask clients to see others for a variety of reasons. YOU ARE ASKED TO SEE THE CLIENT TO: determine degree and type of loss prior to or after medical intervention determine degree and type of loss because the client complains of hearing loss monitor the effects of a noisy working environment determine reasons for communication difficulties assess clients at high risk for hearing impairment assess the need for amplification or other device/s YOU ASK THE CLIENT TO SEE ANOTHER BECAUSE: there is a conductive loss or asymmetry * the client complains of medical symptoms, e.g., dizziness, tinnitus pain, discharge, fluctuating hearing loss * the client experiences difficulties in their working life the client experiences educational difficulties the client experiences speech difficulties greater than would be expected from the audiogram they would benefit from the support of a self help group Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 38 *Ask the client to see their GP, possibly for ENT or other specialist referral. If you feel a client should see a specialist medical practitioner you can only suggest this to the GP. The GP then arranges for a referral if they believe this is the best action to take. Any time you are uncertain about the hearing results you should consider asking the client to see someone else. At this stage of your training, all results should be discussed with your supervisor and you should ask your supervisor for direct assistance when you suspect the client is not responding as well as they should, when there is asymmetry and when there is an atypical audiogram. Monitoring referral It is easy to lose track of clients who you have asked to see someone else. If you wish to see the client again or if you wish to know what happened you will need to monitor the referral. You may find your clinic has certain methods for this or you could simply write in your diary e.g., select an appropriate length of time and write ‘Review Mr/Ms_ _ _ _ _’ Writing reports Reports are written for many reasons. The reason the report is written will affect how it is written. You should adjust how you write the report to suit the person who is to receive the report. Reports should include: a) an opening statement as to why the client was seen, e.g., ‘Thank you for referring Mrs Y.’ ‘Mrs Y arranged an assessment as she has been experiencing increasing difficulty with her hearing.’ b) a description of the audiogram including type and degree of loss, e.g., ‘Pure tone audiometry shows a bilateral, symmetrical, mild-moderate sensorineural hearing loss.’ or keep it simple, ‘Hearing test shows a mild-moderate sensorineural loss in both ears’. It is difficult to keep a report completely simple but most people working with the hearing impaired will know the basic terminology. c) a statement about what action was decided on, e.g., ‘Mrs Y has decided to trial a hearing aid in the left ear.’ ‘I have asked Mrs Y to see you as she would like to talk to you about medical options before proceeding with a hearing aid.’ d) a concluding statement, e.g., ‘If you require any further information please contact me. I am available on 02 9777 7777 on Mondays and Wednesdays.’ Reports can be handwritten but if nobody can read them they are useless. Many clinics have printed report forms or templates on computer. You should always keep a copy of the correspondence you send and make a note of the people they were sent to. The more practice you get writing reports, the better you will be. One useful practice is to keep samples of good report writing. Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW 3064-9/HLSP Audiometry – Assessment A V1 39 TOPIC QUESTIONS If you can answer all of these questions with confidence (and without looking at your notes) then you should be ready for assessment events that will ask you to apply your knowledge and skills in audiometry. You should be prepared to answer questions from clients, teachers and supervisors. If you do not know the answer of a reasonable question, write it down and do the research and learning to be able to answer it the next time it is asked of you. You should then check with your supervisor or teacher that you are able to answer the question. What are you doing when you perform audiometry? What is a subjective test? What is an objective test? Why do you need a quiet test environment? How do you know a test environment is quiet enough? How do you seat a client? What is a hearing threshold? How do you instruct the client to respond in a hearing test? What might happen if you do not place earphones correctly? When would you use insert earphones? In what order do you test the frequencies? What is the rule for testing mid-octave frequencies? Which ear do you test with a bone conductor? Why must you present the sounds in a hearing test randomly? How do you treat clients experiencing tinnitus? What are tactile responses? Describe degree of hearing loss. How is type of hearing loss described? How is type of hearing loss shown on the audiogram? How do you explain the results of a hearing assessment to clients? What is 3FAHL and how do you derive it? Why establish SRT? What is the purpose of speech testing? Why would you test speech at 3FAHL + 30? Can you refer directly to an ENT? What 4 components should a report include? When would you ask the client to see someone else? Developed by Community Services, Health, Tourism and Hospitality Division © 2004, TAFE NSW
