Basics of Audiometric Testing
Setting up a Hearing Check (Audiometry) Program
Audiometric testing programs can be accomplished in several different ways. Making the best choice usually depends on knowing what your company needs and understanding the advantages and disadvantages of the model options and selecting the option that makes the most sense for the employer and employees.
In general, the broadly used models can be categorised as:
- In-house: the employer has dedicated space, equipment, and personnel to conduct the hearing tests on-site.
- Mobile service provider: a third-party service provider comes to the job site with equipment and personnel to conduct the tests, typically in a mobile van or trailer.
- Off-site medical/audiology clinic or hospital: workers travel to an off-site facility that offers hearing testing services.
- Combination: using two or more of the models to complete the baseline, annual, and follow-up tests.
Audiometric test programs need qualified people to perform testing on workers as well as appropriate medically or audiologically qualified professional to conduct further assessment and determine follow-up actions when a significant threshold shift are present. All testing should be performed by a competent person, appropriately trained and experienced in using procedures and equipment that comply with AS/NZS 1269.4.
If you are setting up an in-house audiometric testing program, you will need several pieces of equipment. The typical equipment list includes:
- Audiometer: A device used to measure the sensitivity of hearing with pure-tones of various frequencies. The audiometer has earphones that must be calibrated to the audiometer. There are different types of audiometers, including manual, microprocessor, and computer-controlled.
- Otoscope:A bright light with a magnifying lens that is used to view the outer ear and eardrum. It is helpful to know the condition of the ear canal before doing a hearing test and when inserting hearing protection devices.
- Performance Checking - Bio-acoustic Simulator: A specialised device that is used to verify the performance of the audiometer. Each day that hearing testing is to be done, the technician places the earphones onto the simulator and a quick check of its hearing thresholds is performed. Changes in thresholds of the bioacoustic simulator can indicate a malfunctioning audiometer.
- Audiometric database management system: A commercial software program specifically designed to collect, analyse, and store audiometric data and related hearing conservation information. Using an audiometric database management system can help with recordkeeping, generating reports, and trend analysis.
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What is a “Problem Audiogram”?
Examples of problems audiograms are audiograms that show large differences in hearing thresholds between the two ears, audiograms that show unusual hearing loss configurations that are atypical of noise-induced hearing loss, and audiograms with thresholds that are not repeatable.
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How do you use Audiograms?
Audiograms are used to document existing hearing loss, detect any deterioration of hearing and appropriate rehabilitation. It does not measure the effectiveness of noise control measures or the causes of any hearing damage or injury.
Recommended procedures for audiometric testing can be found in AS/NZS 1269.4.
Some Australian regulations have a general requirement for medical surveillance of people occupationally exposed to hazards, a requirement which has been interpreted to mean that audiometric surveillance is required for people occupationally exposed to noise. Some jurisdictions have specific requirements for provision of regular hearing tests for people whose noise exposure is such that they need to rely on hearing protectors for protection.
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Significant Threshold Shift
A threshold shift as noted in SWA COP, refers to a shift in the auditory threshold and can be temporary or permanent, resulting in temporary or permanent hearing loss respectively. Any confirmed threshold shift should lead to action as described in AS/NZS129.4 Section 9.
A significant threshold shift is defined as:
- (a) a shift in average threshold at 3000, 4000 and 6000 Hz greater than or equal to 5 dB; or
- (b) a shift in mean threshold greater than or equal to 10 dB at 3000 and 4000 Hz; or
- (c) a change in mean threshold greater than or equal to 15 dB at 6000 Hz; or
- (d) a threshold shift greater than or equal to 15 dB at 500, 1000, 1500 or 2000 Hz; or
- (e) a threshold shift greater than or equal to 20 dB at 8000 Hz.
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Abnormal Thresholds
Normal hearing thresholds are in the range of 0 – 25 dB hearing level (dB HL). Thresholds that are greater than 25 dB HL are said to be outside the normal range and indicate that a hearing loss is present. There are typical patterns of hearing loss, sometimes associated with the cause of the hearing loss.
Thresholds that are either outside the normal range of hearing or atypical for a type of hearing loss are considered to be abnormal.
When thresholds are abnormal, more attention is needed in order to determine the best approach to managing the hearing loss and worker.
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Invalid Tests
There are times when test results are either incomplete, were not done according to the regulatory requirements, or do not represent the actual hearing ability of a worker. Invalid tests cannot be used to meet regulatory requirements and do not serve the purpose of identifying early stages of noise-induced hearing loss. Sometimes the test can be repeated to correct errors, either due to improper testing protocols or equipment malfunction. Other times a worker may need to be referred to an audiologist for more comprehensive testing.
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Significant Threshold Shift Follow-Up
Occurrence of significant temporary or permanent threshold shifts or tinnitus in your audiometric results can indicate that the hearing conservation program (or noise management program) may be failing, and review of control measures to determine if more effective measures can be implemented should ensue.
Actions to affect this could include:
- Reviewing job tasks of affected worker/s to ascertain if any changes to work practices may have increased exposure to noise and/or ototoxic substances
- If necessary, re-determine exposure to noise and/or ototoxic substances
- Verify if personal protection equipment provided for ototoxic substances is adequate and properly used, and if HPDs are adequate for the level of noise exposure of affected worker/s. If HPDs are inadequate, alternative hearing protectors with more attenuation must be provided, as well provision for refitted and retraining workers on HPDs.
- Examine HPDs of affected worker/s to ensure they are well maintained and in good condition.
- Check if worker/s uses HPD correctly and consistently during job task
- If additional testing is needed, or if there is a reason to suspect that the HPDs are causing a medical problem, the worker should be referred for an audiological or medical evaluation.
- The worker must be informed of the need for a medical examination if it appears there is a medical condition that is not related to the use of HPDs.
Resources to Learn About Audiometric Testing
Noise, SafeWork Australia
See “Codes and Guides”Model Code of Practice: MANAGING NOISE AND PREVENTING HEARING LOSS AT WORK: September 2018.
This page also includes links to State and Territory Regulators for specific local requirements.
The Australian Standard AS/NZS 1269 series, Occupational noise management (1 – 4), provides technical requirements and guidance on all facets of occupational noise management.
Audiometric testing and assessment of audiograms should be carried out by competent persons in accordance with the procedures in AS/NZS 1269.4:2005 - Occupational noise management - Auditory assessment.
Australian audiometry regulations
SA,NT, Tasmania, ACT, Commonwealth
- Worker Health and Safety Act 2011, Regulation 58
Western Australia
- Workers Compensation and Injury Management Act 1981
- WHS Bill
Queensland
- Regulation 58 repealed, but employers have “primary duty of care” to monitor health of workers
- Employers directed to follow Code of Practice for Managing Noise and Preventing Hearing Loss at Work
NSW
- Exemption for “Clause 58” (audiometry) until December 2020
- Employers encouraged to follow Code of Practice for Managing Noise & Preventing Hearing Loss at Work
Victoria
- OHS Regulation 2017, Part 3.2
Several states – Mining-specific health surveillance regulations
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IMPORTANT NOTE: This information is based on selected current national requirements. Other country or local requirements may be different. Always consult User Instructions and follow local laws and regulations. This website contains an overview of general information and should not be relied upon to make specific decisions. Reading this information does not certify proficiency in safety and health. Information is current as of the date of publication, and requirements can change in the future. This information should not be relied upon in isolation, as the content is often accompanied by additional and/or clarifying information. All applicable laws and regulations must be followed.
