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:
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:
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.
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 language
Thresholds 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.
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.
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:
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