audiometry

Industrial hearing loss


Learning resources

Required text:
To complete the competency (HLTAU2A) Conduct screening hearing tests for adults you must have access to a copy of the following:

TITLE AS/NZS 1269.4:2005 Occupational noise management - Auditory assessment
PUBLISHER Standards Australia
ISBN 0733717667
CONTACT DETAILS
Relevant texts
There are other texts that can help you with this topic. The following textbooks are all relevant and you may decide to refer to them as you study this topic.

TITLE AS/NZS 1270 Acoustics – Hearing Protectors
PUBLISHER Standards Australia
CONTACT DETAILS: http://www.standards.com.au/catalogue/script/search.asp

TITLE Attenuation of Hearing Protectors
AUTHOR National Acoustic Laboratories
PUB DATE 1989
PUBLISHER AGPS, Canberra

.TITLE Principles of Hearing Aid Audiology
AUTHOR Maltby, M.Tate
PUB DATE 2001
PUBLISHER Whurr Publishers, UK
ISBN 1861562578

TITLE Introduction to Audiology
AUTHOR Martin, F.N. & Clark, J.G.
PUB DATE 10th Edition, 2010
PUBLISHER Allyn & Bacon, USA
ISBN 0-205-36641-4

TITLE Handbook of Clinical Audiology
AUTHOR Katz, J. et al.
PUB DATE 4th Edition, 1994
PUBLISHER Williams & Wilkins, Baltimore. Md.
ISBN 0683006207

Introduction

Workplace audiometry fulfils a number of roles:
• It establishes the sensitivity of an individual's hearing and provides them with feedback about their hearing levels. It allows for discussion of the client’s results with them.
• Workplace audiometry will help to identify those employees requiring further medical examination as a result of ear pathology not due to noise trauma. Those workers identified with problems in their outer or middle ears should be referred to their GP for medical treatment as required.
• Workplace audiometry provides an opportunity to educate the workforce about noise and its effects on hearing. Hopefully this will motivate the workers to act to protect their hearing.

This unit relates to screening programs. Screening programs are used in a number of different places but the purpose of all screening programs is to establish quickly and inexpensively if there is a need to be concerned and the people that need further testing.

Standard AS/NZS 1269.4 – 1998, Occupational Noise Management: Auditory Assessment outlines who should be tested. The Standard specifies that people in the workforce exposed to noise levels in excess of LAeq, 8 hours of 85 dB(A) should have audiometric monitoring. That is LAeq, 8 hours of 85 dB(A), is the amount of noise exposure that would occur if the noise level was 85dB(A) for an eight hour period. If the noise is louder, the time required to reach the same LAeq would be reduced, eg. at 88dB(A) it would take 4 hours. This requirement applies even if hearing protection is available and worn.

There are 7 elements of competency and performance criteria for this competency:
1) Prepare for screening tests.
2) Establish a positive relationship with the client.
3) Conduct otoscopy.
4) Conduct further screening tests.
5) Review test results with client and their carer.
6) Refer client to appropriate facility.
7) Clean and store equipment.


Prepare for screening tests

The information, including required forms are accessible and ready for use
What sort of information do you need to conduct a screening test for industry related hearing testing? The information you need may include: client medical history; referral letter; consent form; correspondence; previous test results; current Standards; client medical history; referral letter; consent form; correspondence and previous test results.

The forms you use will impact on how easily and reliably you report the test results.

Client medical history

The choice of medical history form will depend on the reason for doing the hearing test. When you are testing for screening purposes in a workplace setting the form should be brief. It is possible to design a form that can be completed by the client on their own or you can design a form that will take a short time only. The history should take no more than 3 minutes to complete as the testing is part of a mass screening program and, therefore, should not take long to complete. The history form should include the following minimum requirements:
• Name of the client.
• Client’s date of birth.
• Has the client experienced tinnitus, vertigo, ear ache or discharge?
• Has the client had any ear operations or medical treatment for the ears? If so, the details should be written down.
• Is there any family history of hearing loss?
• What is the client’s history of noise exposure, including recreational and military?
• The type of hearing protection used and, if the client brings their hearing protection with them, the state of the hearing protection.
• The audiometer used to perform the test.
• The name of the tester.
• The date of the test.
• A signed agreement that the results of the assessment can be disclosed to the employer.

Sample history form

historyform.png


Referral letter
You may or may not receive a referral letter to test the client’s hearing. In a mass screening program it is likely that you will be given a list of names for workers who need to have their hearing tested. You should ensure that you keep a record of who has attended so that you can inform the employer.

Consent form
Consent may be written, verbal or implied. In mass screening programs you cannot rely on verbal or implied consent. You must have a written consent from the client allowing you to disclose the information from the assessment to the client’s employer. This could be incorporated on the history form. You should be prepared to answer any questions about why this is necessary. If the worker is concerned about how the information might be used you should be able to explain the reasons for the screening program.

Correspondence
Correspondence may include any special instructions for undertaking the screening program, who is to be tested and to whom the reports are to be sent.

Previous test results
The major purpose of undertaking a screening program is to establish when there has been a change in hearing levels for individuals employed in the organisation. The only way to establish this is to have access to previous test results especially the pre-employment test results.

Further testing will need to be undertaken if there has been a deterioration in hearing levels.

The Worker's Compensation Act requires that audiometric testing of new employees is carried out prior to the commencement of work in a designated hearing protection area. This ensures that all workers who move into a noisy environment undergo audiometric testing. For existing employees, audiometric testing should be carried out at the commencement of a hearing protection program and at regular intervals.

Current Standards

The most important source of information is the standard AS/NZS 1269.4 – 1998, Occupational Noise Management: Auditory Assessment.

What is a standard and why do we have them?
A standard is an agreement for the same practices to be followed. That is, a group of people get together and decide what should be done and how it should be done.
There are standards for hearing measurement. These standards relate to occupational practices not to the whole range of audiometric assessment. That is, the standard for hearing assessment relates to how audiometry should be carried out in the workplace.

The main standard in Australia and New Zealand is AS/NZS 1269:1998: Occupational Noise Management. The most important part of this for you is the fourth section.

The AS/NZS 1269.4:1998 is one part of five sections of the Australian and New Zealand Standards for occupational noise management. It was released in March 1998 and superseded the document known as AS1269 - 1989. Section AS/NZS 1269.4:1998, is titled Auditory Assessment and deals with setting up and practising workplace audiometry in Australia and New Zealand.

The other 4 parts of AS/NZS 1269 – 1998 Occupational Noise Management are:
AS/NZS 1269.0 – 1998 Overview
AS/NZS 1269.1– 1998 Measurement and Assessment of noise immission and exposure
AS/NZS 1269.2– 1998 Noise Control Management
AS/NZS 1269.3– 1998 Hearing Protector Program

Section 7 of the Standard AS/NZS 1269.4:1998, Auditory Assessment, looks at the capabilities of the tester. The tester should be properly trained in basic pure tone audiometry, understanding the test procedure and how to manage any clients with any hearing problem detected. The tester should also understand the relevant legislation and codes of practice. The test procedure set down in AS/NZS 1269.4:1998 should also be fully understood and practised by the audiometrist.

Assessing the environment for screening test suitability

Most screening programs take place at the work-site. This helps to make them cost-efficient by reducing the amount of time workers are absent from their duties. However, this means that it is unlikely that the environment will be ideal. The standard 1269.4 sets out the maximum acceptable limits for background noise.

Section 6 in the Standards deals with the ‘acoustical environment for audiometry’. The level of noise in the room you are to be testing in will impact on the reliability and validity of the test results. Therefore the Standards outline how to measure the background noise level and interpret these measurements. We will look at this in more detail shortly. It is also important to have a comfortable testing environment as well as a quiet one. The room should be well lit and at a comfortable temperature. The room you choose to test in should not be too visually distracting and should be situated away from main traffic areas at the work-site. Ideally it should not be next to the toilet, reception area, tearoom or photocopier. Sometimes it is difficult to find such a room! However if you cannot test in a room that is reliably quiet, then it is possible that your results will not be accurate.

The test room should also provide privacy so that the client cannot be seen while being tested and that any discussion that may take place cannot be overheard.

Ambient Noise

What is ambient noise?
Ambient noise can be defined as the surrounding noise within the test environment. That means any noise within the vicinity of the room that will impact on the background noise levels. For instance, you may be provided with a room to test in that appears quiet on your initial inspection, however during your testing, forklifts may be circling outside or it may be raining on the tin roof. These types of ambient noise will increase the background noise levels within the test room, and may make the test environment unsuitable to obtain valid and reliable test results.

The testing environment needs to be quiet for reliable results to be obtained. If the ambient noise is loud enough, the worker will be unable to hear the sounds and it may seem that they have a hearing loss. The effect of ambient noise is most obvious in the low frequencies.

The Standard outlines the maximum acceptable background noise levels for audiometry at each frequency and for different types of earphones and earphone enclosures. Refer to your copy of the standard AS/NZS 1269.4:1998. There is a table in the standard that gives the maximum acceptable background noise levels.

Measurement of background noise levels
How do you know that the environment is suitable?
The instrument to be used when recording the background and ambient noise levels is the sound level meter (SLM). There are a number of types of SLMs. Each type being able to perform different sorts of measurements.

A Type 1 SLM is required for assessment of background noise levels for work-site audiometry. This type of SLM will be able to carry out octave band analysis. Type 1 SLMs have a pressure response microphone. Type 2 and Type 3 SLMs do not have this capacity for measurements and cannot be used for background noise assessment and reporting.

Type 2 SLMs can be used for noise surveys. They are not as accurate as Type 1 SLMs and therefore, should not be used in marginal situations. Type 3 SLMs are only to be used for preliminary assessments that are sometimes called “walk-through audits”.

Type 1 SLMs are very expensive pieces of equipment and may be an expense your service can afford. If you are going to do workplace audiometry, it is advisable that you have this piece of equipment or have access to a Type 1 SLM. They can be rented from companies who manufacture and/or calibrate SLMs or sometimes the work-site you are visiting will have one that you can take the measurements with. Using a SLM does take some practice and the Standard outlines how the measurements should be taken.

The other, lesser types of SLMs do have their uses, but obviously cannot perform the same functions as Type 1 SLMs. Type 3 SLMs, in particular, have limited uses and often cannot be calibrated. They can be used to gauge ‘ballpark figures’ of noise levels, but should really be only used as a guide. They are very inexpensive instruments and can be obtained from major electrical retail stores. But remember, they are only a screening device, not an accurate measure. Type 2 SLMs can provide detailed measurements of noise using different weighting systems in accordance with AS/NZS 1269.1:1998 Part 1: Measurement and assessment of noise immission and exposure. Again these are fairly expensive instruments and are usually used for noise surveys of a work-site.

There is one other type of SLM – Type 0. These are the most accurate SLMs but are generally only used in research and development situations.

It is advisable that some basic training in the use of SLMs is sought before using them in a professional setting. Many short courses are available from the manufacturers or other training institutions.

You may notice from the table that octave band level measurements are taken for the frequencies 125, 250, 500, 1000, 2000, 4000 and 8000Hz. A sound level meter (SLM) will be required to test the background noise levels in accordance with the Standards. These outline how to set up the SLM and take octave band measurements. The background noise levels of the test environment will need to be assessed to determine a quiet and therefore reliable test environment. All measurements will be taken during normal activities and services operating as expected during the audiometric testing time.

Steps for using a SLM:
1. Calibrate the SLM by taking the piston phone calibrator (these should be supplied with all Type 1 and Type 2 audiometers) and placing it over the SLM’s microphone. The make and age of your SLM will determine the next steps to calibration of the SLM. You need to calibrate your SLM before every measurement session and after to ensure it did not go out of calibration during the measurement session.
2. Once Calibration is completed set your SLM to the ‘linear’ weighted measurement and ‘S’ (for slow) time weighting. If your SLM has an octave band filter start your testing at 125Hz.
3. If your test room is small (no bigger than 2 chairs and table size) you will probably only need to take one reading for each frequency. If the room is bigger you may need to take a number of readings for each frequency.
4. Take a measurement for each frequency of at least 60 seconds duration.
5. Record your readings at 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz and 8000Hz.

The levels you have measured will be used to determine the type of earphone combination to be used during testing.

There are different types of earphones on audiometers. Many will also have an enclosure around the earphone to help with noise exclusion. This information will impact on the maximum acceptable background noise levels for testing.

Do your earphones provide a quiet enough (and therefore reliable) test environment? Compare the acceptable background noise levels to the actual background noise levels.

Equipment and attachments for assessments are checked and calibrated ready for use
AS/NZS 1269.4:1998 has 10 sections dealing with workplace audiometry standards. Section 5 deals with the type of audiometers to be used and the care and maintenance required for the audiometer to be a reliable instrument. Importantly an audiometer should be calibrated (tuned) annually. However if a fault is found at any time, your audiometer needs to be repaired and re-calibrated. To detect a fault, a ‘daily listening check’ should be carried out prior to testing each day. This procedure should only take a couple of minutes at the beginning of the testing day, but its importance cannot be underestimated. A basic daily listening check should include the following:
• Checking earphone cushions for hardened rubber or cracks.
• Checking the tension of the headband for the earphones and that all wires are untangled and straightened.
• Checking for loose dials and/or clicks when turning the dials on the audiometer.
• Checking that the sound through the earphones is free of static or noise due to faulty leads. Turn the attenuator dial to 40dB at 1000Hz and listen to the tone while twisting the leads of each earphone separately.
• Checking for gross linearity at 1000 Hz by setting the attenuator at 10dB and then increasing it in 10dB steps up to 90dB. You should check that the increases in loudness are roughly equivalent for each 10dB increment. This should be done for each earphone.
• Checking for 'cross-talk'. This is done by pulling one earphone off or turning the earphones in opposite directions. Then hold one earphone up to your ear and put a tone through the OTHER earphone. No sound should be heard in the one held to your ear. Repeat procedure for opposite earphone.
• Performing subjective calibration check by assessing your own thresholds. You should have your own hearing checked regularly and know what your levels are. Check them during a daily listening check and ensure they are within 10dB of your normal levels at every frequency. If they fail this criterion the audiometer cannot be used and must be sent off for calibration and repair.
When packing the audiometer for annual calibration all leads must be unattached and wrapped separately in a cushioning material. The audiometer should be placed in a cardboard box and firmly packed with foam and/or newspaper to protect against any damage occurring in transit. If your audiometer has its own carry-case then pack this securely in a cardboard box before transportation. The box should be marked 'Handle With Care'. In normal day to day transportation of the audiometer always secure it firmly in the car eg with a seatbelt.

Personal protective equipment is available and used if required

Workplace audiometry sometimes requires you to go to work-sites that have specific requirements for personal protective equipment or a dress code for safety purposes. You are required to comply with the requirements of the workplace so it is best to check before the day of testing if there are any such requirements.

For example, closed shoes, steel-toed boots, long sleeves, no loose clothing, hardhat, hearing protection, hair tied back, gowns, caps, gloves.

You should make sure to take whatever you are likely to need.


Establishing a positive relationship with the client

It is expected that you will have completed the learning guide HLT02-4 Client Interaction before starting this competency. If you have not you will need to do it before proceeding.

Consider the clients you are likely to meet when performing workplace audiometry. Some of your clients may be reluctant to undergo hearing testing and some may require reassurance about the purpose of the screening program. Your clients are not just the people who will be having their hearing tested but will also include the person or people who have organised for the screening to take place. You have responsibilities towards all of these people and you need to be able to deal with each of them in a professional manner.

The test procedure is explained clearly and simply to the client
The way you explain the test to the client will have an impact on how efficiently the test is done. If the client is unsure about what you want them to do then they may not be responding the way they should.

What is the test procedure? You need to be sure you understand what this is so that you can explain it to the client. There is a discussion about instructing the client in the learning guide for Assessment A. Take the time to review that information now.

Informed consent is gained from client where applicable
As discussed previously informed consent may be verbal, written or implied. However, when testing in a workplace environment the only adequate consent is written consent.

Informed consent means that you have explained to the client what the assessment is for, what the test procedure is and what the assessment will be used for.

Client is given the opportunity to ask questions and discuss concerns
You must give the client an opportunity to ask questions and discuss any concerns they might have. Sometimes you may need to be very clear and ask questions like:
“Do you understand what we will be doing?”
“ Would you like to ask me any questions?”
“Do you have any concerns about the test?”

Special needs of client are identified and met
What do you think special needs might include?

Special needs may include anything that affects the client. If the client has a physical disability you may need to adjust the environment to allow the test to take place. If the client has a developmental disability you may have to adjust how you instruct the client and explain the results to them. You may need to reassure the client about how they are doing. If the client has a non-English speaking background you may need to have an interpreter available.

Confidentiality of client information is maintained
It is important that you do not discuss the test results of a client with anyone else unless you have permission to do so. It is also important that you do not leave a client’s test results in a location that can be accessed by people who do not have permission to see the results. For example, you should not leave a client’s test results in clear view of other clients.

As an allied health professional you are expected to be very careful with the information you have about a client. Client confidentiality is important legally and ethically. There is an implied confidentiality whenever you see a client and you are not permitted to discuss the client with someone when there is no permission to do so.

Check with your professional organisation about their code of ethics. You will find there will be some discussion of confidentiality.

Secure location for written records
Confidentiality also relates to the storage of files. For example, it would not be appropriate to leaves files in an unlocked filing cabinet in the waiting room. There are times when a waiting room would be unattended and it is possible that someone could look through other people’s files and find out personal information that would distress the other client.

Consulting rooms with privacy
It is vital that you have a room that does not allow people to listen in to what you are discussing with a client and their carer. Many people will feel uncomfortable if they can be seen while doing the test.

Disclosure of information
Information should only be disclosed to an appropriate person consistent with the responsibility of the position. This means that you need to establish who that person is before you start discussing the results of the assessments. This can be done at the beginning of the project by asking.

Adherence to Privacy Act
You can look at the website http://www.privacy.gov.au/act/ to understand your legal obligations. See especially the 10 principles of privacy.


Conduct otoscopy

Have you completed the learning resource for Otoscopy? If not, it is now time to do it.

Personal hygiene and infection control procedures followed
Following personal hygiene and infection control procedures may be very difficult when testing at a workplace. One of the most important procedures is washing your hands. This may not be possible when there is limited access to hand washing facilities. You may need to plan to use other methods such as the use of gloves. You may need to consider the use of disposable speculae or taking adequate speculae for the number of clients you expect to see.

Otoscopy is conducted to produce valid, reliable, and accurate results and in accordance with relevant policy and procedures
Performing otoscopy in the workplace is no different to performing otoscopy in the clinic. If you are competent in otoscopy, you will be able to determine what you are observing.

You should make sure that you have spare batteries with you or if using a rechargeable battery, that it is fully charged for the day’s work. You cannot obtain valid, reliable and accurate results with a dull light on your otoscope.

Contra-indications for proceeding with further screening tests are identified
Contraindications for proceeding with further screening tests include excessive cerumen, the presence of a foreign body, discharge from the ear and otalgia. If the client experiences any pain during otoscopy, you should ask them to see their Family Doctor. Testing will have to be arranged depending on the Doctor’s advice to the client. It is important to make a note of why the test could not proceed.

Referral is made to appropriate agency for further assessment and treatment if required
If otoscopy reveals a contra-indication to testing, you should ask the client to see their Family Doctor. It is best if the client can be given a letter explaining why you have asked them to see their Doctor. You will need to get their permission to give the information to the Doctor. You will also need permission to provide the information to the employer.


Conduct further screening hearing test

Hearing screening for workplace testing is outlined clearly in Standard AS/NZS 1269.4 – 1998: Occupational Noise Management: Auditory Assessment. Most mass screening programs will use monitoring audiometry.

Personal hygiene and infection control procedures followed
As discussed above this may present a challenge in the workplace.

Screening hearing tests are conducted to produce valid, reliable and accurate results and in accordance with relevant policy and procedures
After taking the case history, performing otoscopy and instructing the client you will test the client’s hearing. You must be careful to place the headphones correctly. The client must not place the headphones on by themselves and should be instructed not to change the placement of the headphones. Many clients feel that the headphones require adjustment but you may need to explain to the client that the headphones must be placed in a very particular way to ensure the best results are obtained.

Workplace audiometry technique is purely an ‘ascending’ procedure. That is, at each frequency you must begin testing at 0dB and go up in 5dB steps until a response is made by the client. You then go back down 10dB and ascend again to the threshold in 5dB steps, but present the tone three times at each step, until the client responds more than once at a level. This level may well be the threshold, but to check you must decrease the level by 5dB and present three tones at this level. If the client does not respond, or responds only once, the level 5dB above is taken as the threshold and recorded on the audiogram.

There is a very clear outline of how to conduct hearing tests in Standard AS/NZS 1269.4 – 1998: Occupational Noise Management: Auditory Assessment.

Guidelines for the two types of tests to be undertaken by the audiometrist for workplace audiometry are outlined in Section 7. Reference audiometry is used to establish the initial status of an individual's hearing. This audiogram represents the level from which future changes in hearing thresholds will be calculated. It is therefore recommended that this audiogram represent the average of at least two initial audiograms taken in one session, with earphones being removed between tests.

Monitoring audiometry is used to establish any subsequent changes from the reference audiogram. Ideally this should also be the average of two tests, although a compromise based on two tests, if the first one is significantly different from the reference audiogram, is also adequate.

For accurate results, reference audiometry requires 16 hours of pre-test noise free time, with the hour before the test being particularly important (noise levels down to less than 75 dB(A)). Monitoring audiometry should take place well into a work-shift so that any temporary threshold shifts that occur due to the inadequacies in the use of hearing protection will be exposed.

For reference and monitoring audiometry, thresholds for the frequencies 500, 1000, 1500, 2000, 3000, 4000, 6000Hz and 8000Hz should be obtained. The test order for the frequencies is: 1000, 1500, 2000, 3000, 4000, 6000, 8000, 500 Hz and finally 1000Hz (again). If the thresholds for the same ear at 1000 Hz do not agree within 5 dB, then the result of the second test at 1000Hz should be used.

Clients should be encouraged to bring their personal hearing protection to each appointment so that these can be inspected to ensure they are in good condition and that they are being worn correctly.

Recording of the results is also outlined in Section 7. These are fairly similar to the requirements of most tests. These requirements include date of test, name of employer, calibration date of audiometer, compliance with background noise levels, type of earphone/enclosure used, personal details of client, case history information, (including noise exposure history), state of client’s ear canals, audiometric symbols recording the actual hearing results and a signed consent by the client to release the results to the employer.

Section 8 in the Standard deals with the actual test procedure required when testing in the workplace. It discusses how to prepare the client for the test and how to place the earphones. Incorrect placement of earphones can influence the reliability of the test results. The client needs to be told what is required of them during the test (e.g., how they are to respond to the tones). These instructions should be given prior to placing the earphones. The required test procedure is then outlined. Manual and automatic audiometry requirements are discussed.

Steps taken to maximise test accuracy, validity and reliability
How would you meet the guidelines set out in the Standards to ensure that your test results will be valid and reliable? What are the steps that you would take to ensure that a quiet test environment has been found?

If test results unreliable, a re-test is conducted
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 clinician.

What are the sources of variability in test results?
• The tester
• The client
• The test conditions
• The equipment
• The headphone placement

Recognising unreliable test results
You may suspect that the client is not responding to the softest sounds that they can hear if:
• They respond appropriately when you speak to them in a soft voice without visual cues.
• They give no responses at all for one ear.
• They give inconsistent responses.
• Their responses are exaggerated.
• There is an indication that they can hear the sound but they do not actually respond. For example, their arm moves but they do not make the response that indicates that they have heard the sound.

When you have recognised that the client may not be giving you a reliable test result you then have to determine how to achieve a reliable test result.

The first step is always to give the client the benefit of the doubt and reinstruct them. Clients who are deliberately trying to make it appear that their hearing is worse than it actually is are unlikely to admit to it. If you force a confrontation it is unlikely that you will achieve reliable results. Remember though, that this is a mass screening program and this would be one of the reasons for recommending further testing. You do not have the time to deal with a difficult test situation. You must be careful how you write your comments about the client. For example, “Best responses show a hearing loss but further testing is required as Mr/Ms X was not reliable in their responses despite re-instruction.” This shows quite clearly what happened without negative personal comments being made.

Headphone placement
One important aspect is the correct placement of the headphones. The Standard requires that if there is a loss at 6kHz and/or 8kHz then the headphones need to be removed, repositioned and those two frequencies retested. If the threshold improve after repositioning the headphones then it is worthwhile retesting the other frequencies quickly to make sure that you have obtained threshold.

Strategies to meet Australian Standards
There are many strategies you could employ to ensure successful testing at the work-site. The following are all important and should be adhered to, to ensure a professional standard is always kept.
• An audiometer in good working order that has been calibrated within the last 12 months and which has a daily listening check carried out.
• Measurement of background and ambient noise levels by a Type 1 SLM and evaluated in conjunction with the type of earphone and earphone enclosures to be used during the testing. Choosing a room that has carpeting on the floor and/or heavy curtains on the windows may be beneficial. Placing signs outside the door saying “Quiet Please! Hearing tests in progress” are often a simple and effective way to keep background noise at an acceptable level as is ensuring that the workforce has been notified of the impending hearing tests and that they are aware of the need for quiet around the test area.

• Ensuring the employee is aware of why the test is taking place. Ensuring the employee has consented to the test and for his employer to receive a copy of the results. Is the client well and motivated to do the test correctly? Has the client understood the instructions? Are the ear canals free of occluding wax and/or other abnormalities?
• The earphones must be fitted correctly and not causing the ear canals to collapse. The use of supra-aural earphones is advisable. These type of enclosures will provide extra background noise occlusion for the client. You can see in the Table from Standard AS/NZS 1269.4:1998 – Appendix C: Maximum Acceptable Background Noise Levels for Audiometry that the better the earphone enclosure, the louder the maximum background noise level can be.
• Ensuring that the tester performs the test correctly and in such a manner that the client is not able to determine when the next tone will be presented. The tester should be able to explain the results in a confident and clear manner to the client, so the client understands what is happening to their hearing. If a problem is detected then the tester should refer the client on to the appropriate person for further assessment.

Dealing with Clients Who Can’t/Won’t Co-Operate
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 re-instructing the client.

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 is not well or is unable to maintain the level of concentration needed then your results will be affected. 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.

With experience, you will get a general impression of overall impairment before you start the assessment. 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.

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 co-operate 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.

There are many terms used to when clients won’t co-operate. These include :malingering pseudohypoacusis; non organic hearing loss; functional hearing loss; simulated hearing loss; psychogenic hearing loss or hysterical hearing loss.

These terms imply that the client will not co-operate with the hearing test even though they are capable of doing so. There are ways of assessing these clients but this is not done as part of a hearing screening program. It is always best to obtain a subjective response to sound but if this is not possible then you will need to refer the client to a suitably qualified person.

Certain tests do not require the client’s co-operation. These are called objective tests because the client does not tell you they have heard the sound. There are many different types of objective tests.

Electrophysiological tests are a type of objective test. These include Auditory Brainstem Testing (ABR), Auditory Cortical Testing (ACR), Otoacoustic 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.

Results are recorded in accordance with relevant policies and procedures
The Standard sets out what must be on the results to conform to policy. All audiograms should have the date and the legend for the symbols but the Standard requires more information. Refer to the Standard.

Review test results with client and their employer


Results are examined to determine outcome of screening test
The first step on determining the outcome of the screening test is to ask “Is the hearing within normal limits in both ear?”. If the hearing is within normal limits, the next question is “Are there any indications that noise is affecting the hearing?”.

Noise can affect an individual’s hearing temporarily or permanently. TTS is Temporary Threshold Shift and PTS is Permanent Threshold Shift. The effects of noise on an individual’s hearing produces a characteristic pattern on the audiogram. This was discussed in the learning guide “Pathologies”.

Noise exposure can also cause tinnitus. It is important that the test results are examined knowing whether the client experiences tinnitus.

If the hearing is not within normal limits or there has been a change in hearing levels then further testing may be indicated.

There are other effects of noise that a hearing screening program will not reveal. If the client asks you whether it is possible that they are suffering from the effects of noise you should advise them to speak to their Family Doctor. The following effects have been noted to be related to noise exposure: irritability; headaches; increased heart rate; problems concentrating; fatigue and increased blood pressure.

Outcome of tests are communicated clearly and simply to the client and their employer
Clients are entitled to know the results of their hearing assessment. You should establish who is to explain the results – it will usually be the person doing the test.

Take every opportunity to observe how results are done and take the time to practice explaining results. You can role play this with your peers.

Options for further tests are discussed with client
Whenever there is a hearing loss, further testing is indicated. The client should be informed about their hearing and advised that they will receive information about where to go for the test. To establish whether there is a temporary or permanent hearing loss the client should be tested after some noise free time. The Standard sets out that there should be 16 hours of noise free time.

It is possible that the client will be entitled to compensation if they are found to have a significant, permanent noise related hearing loss. However, it is best to be careful about what you say about this as you cannot be sure what the results of the assessment will be.


Client/employer is given the opportunity to ask questions and discuss areas of concern
Clients are entitled to ask that their results be explained to them. If a brief description of their hearing results is all that they want then this can usually be incorporated in a screening program. However, if the client’s needs require further assessment and explanation then it is better to refer them to someone who is suitably qualified to do the assessment and explanation.

The employer is likely to be concerned about how to reduce the risk of noise injury to their workers. One way this might be done is through a noise management program or a hearing protector program. Standard “AS/NZS 1269.3 – 1998: Hearing protector program” discusses:
• the management’s responsibilities in a hearing protector program
• types of hearing protectors
• selection of hearing protectors
• providing hearing protectors and their fitting
• cleaning and maintenance of hearing protectors
• the designation of hearing protector areas
• training workers to use hearing protectors.

WorkCover NSW has a “Code of Practice for Noise Management and Protection of Hearing at Work” with the purpose of providing an outline of what can be done by employers and workers when there is a possibility of excessive noise exposure. It is available on the WorkCover website and covers many aspects such as: assessing the noise levels of a work-site; an education program for workers; the use of hearing protectors and advice about purchasing equipment.

Results are recorded, documented and filed in accordance with relevant policies and procedures
Reports should be written in easy to understand language without excessive use of jargon. As required in the Standard, the report and results should be made available to the client within two months after testing.

Refer client to appropriate facility

Section 9 of AS/NZS 1269.4 – 1998, Occupational Noise Management: Auditory Assessment looks at the evaluation of audiograms. In other words - what do you do with the results obtained? A copy of the result is to be made available to the client within two months of the test, but the results should be discussed with them at the conclusion of the testing. If a hearing loss is detected, the employee has a right to lodge a compensation claim against his employer for loss of hearing, if it can be proven that the hearing loss was sustained at his place of employment.

Section 9 then goes on to explain how to detect a threshold shift when comparing a monitoring audiogram with a reference audiogram. Importantly, if a threshold shift is detected with monitoring audiometry, a reference audiogram should then be re-established after the client has had a noise free time of 16 hours. If the shift is confirmed, the client should be referred on for further testing and/or medical investigation.

The action to be taken when such a shift in thresholds is discovered will be:
• review the worker’s job
• determine the worker’s noise exposure
• establish any changes that could be made to reduce the worker’s noise exposure
• check the worker’s hearing protection and their use of it.

Referral is made to appropriate agency for detailed assessment if client fails screening test
Prior to starting the screening program you need to consider who is able to perform a detailed test. You may need to provide the organisation with a choice or a costing structure if you will be doing the detailed assessment. A detailed assessment should take place in a location that has a sound treated booth. The personnel at the appropriate agency should have the equipment, knowledge and expertise to undertake the assessment.

Contact is established with referral facility and key client information provided
You may need to contact the referral facility yourself to organise the appointment. It is best to send a letter to the facility with a statement something like: “This client was assessed as part of a screening program at their workplace. Results of the screening test showed that further assessment is required. An appointment has been arranged for this client on _ _ _ _ . Please send a copy of the report to _ _ _ _ . Please send the invoice for the assessment to _ _ _ _ .” You may not send the copy of your test results but many clinicians will prefer f you do. You will have to establish whether your referral facility would like you to send your test results.

Relevant issues and concerns are discussed with relevant personnel at facility
What do you think these concerns are?:
What is the cost?
How long is the waiting list for a test?
What test facilities do you have?
What are the qualifications of your personnel?
Do you have a sound treated booth?
How long before I can expect to see the report?

Can you think of any other issues and concerns?

Referral is followed up with facility to ensure continuity of case management
You should ensure that follow up testing has taken place and that all reports are sent to the client and the organisation.

Clean and store equipment

Screening audiometers and hand held otoscopes are the main types of equipment used for workplace testing . Like all equipment it can be damaged if not handled and maintained properly.

Equipment and attachments are cleaned and/or disposed of in accordance with manufacturers’ requirements and infection control procedures
Guidelines for infection control are provided in the learning guide HLT02-5 - Infection Control. You may need to have alcohol wipes that are easy to carry so that you can clean your equipment at the work-site if necessary.

You should check the manual that comes with your equipment to see if the manufacturer has recommended any particular infection control procedure/s.

You may also need to make sure you have something with which to collect your rubbish. For example, you may need to take at least 3 plastic bags, one for general rubbish, one for recyclable waste and one for contaminated waste.

Equipment and attachments stored in accordance with organisational policy and procedures
Most screening audiometers are easily transported in their own carry case. You should ensure that you have packed the leads and headphones so that they will not be damaged.

As they are valuable equipment it is possible that your organisation requires you to place the equipment in a safe place. Occasionally you may need to take equipment home with you. This will present the challenge of keeping it safe.

NOTES

1. Safe noise levels

A hearing screening program is necessary because some workers will be affected by noise exposure but it is not possible to predict who these individuals will be. Some workers are affected by noise much sooner than other workers. As you can see from the following table it is not just the amount of noise but also the length of time spent in the noise. You may need to consider softer levels of sound if the worker is likely to be in the noisy environment for longer periods of time. For example, if the client does overtime in a noisy environment.

Noise Level Allowable Exposure Time
Noise Level
Allowable Exposure Time
<85dB
No time limit
85dB
8 hours
88dB
4 hours
91dB
2 hours
94dB
1 hour
97dB
30 minutes
100dB
15 minutes
103dB
Less than 8 minutes
106dB
Less than 4 minutes
109dB
Less than 2 minutes
112dB
Less than 1 minute
115dB
NO SAFE TIME

2 Rehabilitation

Rehabilitation assists people to adjust to the disability caused by noise exposure and to overcome many of the negative effects of a noise injury.

You may or may not be involved in the rehabilitation of clients with noise induced hearing loss. Rehabilitation is not a part of a mass screening program but if you are aware of the possible outcomes of noise injury it will help you when you have to explain results to clients (individuals and organisations).

Rehabilitation for noise injury may include any of the following features:
Worker’s Compensation
Communication therapy
Tinnitus Counselling
Hearing Aids
Assistive Listening Devices
Workplace modifications.

3. Ear muffs and Ear plugs

There are many factors in determining whether it is preferable to use ear plugs or ear muffs. It is best to give the workers a choice if this is possible. The manufacturers of hearing protection are willing to work with organisations to help them choose the best product for their workers. Hearing protectors are assessed to establish if they comply with Australia Standards and are given a rating for how much protection is given.

The advantages of ear muffs are:
• Easily fitted
• Usually have good attenuation
• Can be seen easily from a distance so the supervisor can monitor the use of hearing protection
• Can be adjusted while wearing gloves
• Preferable when the hearing protection is removed and replaced many times a day
• Can be worn if there is wax in the ear canal.

The disadvantages of ear muffs are:
• Uncomfortable to wear in hot weather
• Bulky and therefore may be difficult to carry in a tool kit
• May not fit well with glasses
• May be cumbersome in confined work areas
• May be difficult to keep clean
• The initial cost is higher than for ear plugs
• The headband may become stretched and therefore not offer adequate hearing protection.

The advantages of ear plugs are;
• Various sizes are available
• Easily carried, fit easily into tool boxes or pockets
• Can be left in the ear canal for prolonged periods of time
• Can be purchased in dispensers that can be place in convenient locations at the work-site to remind workers to use them
• Initial cost is inexpensive so can be easily replaced.

The disadvantages of ear plugs are;
• They need to be placed in the ear correctly for adequate protection
• Hands should be clean when handling the ear plugs.

Ear plugs can be custom made. This has the advantage that they will fit the client’s ear very well. However, the initial cost is much higher than for standard ear plugs and they must be maintained.