Basics of Audiometric Testing
Setting up a Hearing Check (Audiometry) programme
Audiometric testing programmes 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 categorized 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.
The number of workers who are tested annually is usually a factor in which delivery model works best.
Audiometric test programmemes need qualified people to conduct hearing checks, as well as a professional, either an audiologist or physician, to provide programmeme oversight and review 'problem audiograms.' The term audiometric technician or occupational hearing conservationist (OHC) describes the person giving the tests. Large employers may have access to in-house occupational health services who may be able to carry out audiometric checks. Where there are no in-house facilities you will need to contact an appropriate occupational health service provide which can be found from your local trade association.
Audiologists, physicians or occupational nurses typically carry out audiometric testing.
If you are setting up an in-house audiometric testing programme, 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.
- Bioacoustic simulator: A specialized 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. Technicians often refer to this device as a “Bio Betty” or “Oscar” – names used by certain manufacturers for these simulators.
- Audiometric database management system: A commercial software programme 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”?
A problem audiogram is one which shows large differences in hearing thresholds between the two ears, unusual hearing loss configurations that are atypical of noise induced hearing loss, and audiograms that are not repeatable. Such audiograms must be reviewed by a competent person such as an audiologist, otolaryngologist, or other physician.
The professional supervisor will often guide the employer and/or audiometric technician in identifying problem audiograms.
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Abnormal Thresholds
Normal hearing thresholds are in the range of 0 – 25 dB hearing level (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.
Progression of hearing loss:
20dB – 40 dB Mild hearing loss that may cause difficulty in following conversations in noisy situations.
41dB – 70dB Moderate hearing loss with increased difficulty in communication.
71dB – 95dB Severe hearing loss that may cause significant difficulty in communication in most situations without amplification.
>95dB Profound hearing loss that prevents effective face-to-face communication without amplification, speech reading and/or sign languageThresholds that are either outside the normal range of hearing or atypical for a type of hearing loss are considered as being abnormal.
When thresholds are abnormal, more attention is needed in order to determine the best approach to managing the employee and their hearing loss.
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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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Change in Threshold Follow-Up
Employer’s action on detecting threshold shift – training, better refitting, fit testing, reviewing exposure data, evaluate overall control measures etc.
Results of the audiometric testing programme must be evaluated to determine if the tests are valid and if there is a change in hearing that requires follow-up action.
If a change in hearing threshold is detected consider the following action plan:
- Ensure hearing protection is worn by all workers with daily noise exposure at or above 85 dB(A). Workers who had not been using HPDs before the change in hearing threshold must be fitted with an appropriate HPD, trained on the use and care of the device and worn at all times when exposed to the hazardous noise level.
- You may need to review the HPD issued to the worker for suitability to the job and wearer. If so, alternative hearing protectors with appropriate attenuation must be provided. Workers must be refitted and retrained on HPDs.
- If additional testing is needed, or if there is a reason to suspect that the HPDs are causing a medical problem, the worker must be referred for an audiological or a 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
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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. More information on 3M™ E-A-Rfit™ is available here, you can also contact your local 3M repesentative to hear more and arrange a trial.
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