OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 16 Noise

Section 223 Audiometric testing

The employer is responsible for

(a) identifying noise-exposed workers,
(b) ensuring that noise-exposed workers have hearing tests conducted by an audiometric technician,
(c) paying the costs associated with a hearing test,
(d) keeping a log book containing audiometer calibration data, and
(e) keeping a record of whether the hearing test was done (but not a copy of the actual hearing test).

Any worker who is or may be exposed to noise in excess of 85 dBA Lex and the noise exposure limits in Table 1 of Schedule 3, must undergo audiometric testing. By definition, this worker is considered to be a “noise-exposed worker”. For example, any worker who is exposed or may be exposed to noise greater than an average of 85 dBA over 8 hours, or an average of 82 dBA over 16 hours, must undergo audiometric testing at the employer’s expense.

Audiometric testing of workers’ hearing is important to the success of a noise management program since it is the only way to actually determine if occupational hearing loss is being prevented. Because occupational hearing loss happens gradually over time, workers often fail to notice changes in their hearing ability until a relatively large change occurs. By comparing audiometric tests from year to year, hearing damage can be caught earlier and appropriate protective measures implemented to prevent further damage.

When a worker is or may be exposed to noise in excess of the exposure limits shown in Table 1 of Schedule 3, the worker must receive a baseline audiogram as soon as practicable, but no later than six months after the start of employment. The requirement for a baseline audiogram also applies if a worker is exposed to such noise due to a change in activities (the introduction of new equipment or processes for example) or duties (reassigned to a new job or a new, noisier area within the workplace).

It is usually best that this test be done after a minimum 12 hour period during which the worker is not exposed to any noise. The baseline audiogram is conducted in a noise-free environment when the worker has been away from noise for 14 hours, including noise exposure away from work. For workers who have audiometric testing conducted during their work shift, hearing protection may be used to meet the no noise requirement.

Additional tests are then required 12 months after the baseline test and every two years thereafter. Ideally, these subsequent tests should be scheduled at the end of or well into the work shift so that temporary changes in hearing can be noted. The results can then be compared with the baseline audiogram to check for changes in hearing sensitivity and identify a temporary hearing loss before it becomes permanent. The employer must bear the costs of testing, including time from work, if that is required.

The audiometric test consists of pure-tone-air-conduction threshold testing of each ear at 500, 1000, 2000, 3000, 4000, 6000 and 8000 Hz. At each frequency, the threshold recorded for the ear is the audiometer’s lowest signal output level at which the individual responds in a specified percentage of trials. Noise exposure increases hearing thresholds, resulting in threshold shifts toward higher values (poorer hearing). Exposure to noise usually causes gradual development of hearing loss over time. During each overexposure to noise, the ear develops a temporary reduction in sensitivity, called a temporary threshold shift. This shift reverses over a period of hours or days if the ear is allowed to recover in a quieter environment. If the exposure is to a sufficiently high enough level of noise, of sufficient duration or repeated, the temporary threshold shift may not reverse completely and a permanent threshold shift begins to develop.

Who does the audiometric testing?

The employer is responsible for ensuring that audiometric tests are conducted by a qualified audiometric technician who works in consultation with a physician, audiologist or occupational health nurse. The audiometric technician must keep a log book that contains the audiometer’s calibration records. The log book, and therefore the calibration records, must be kept with the audiometer throughout its useful lifetime. The audiometer must be calibrated at intervals specified by the manufacturer.

Testing area

To determine if the testing environment has acceptable background noise levels must be measured. Background noise levels must be less than those listed in Table 3 of Schedule 3 and must also be recorded and kept with the calibration records. This means that if test equipment is moved to a different location, noise levels must be measured at that new location.

The purpose of conducting background noise level measurements is to ensure that background noise does not interfere with the audiometric testing and give false results.

Record keeping

The audiometric technician must record the results of the hearing test as well as maintain the calibration log books.

Audiograms are confidential medical records and cannot be given to the employer. The employer must ensure that the audiogram and the worker’s medical history are under the sole control of a health professional designated under subsection 223(2)(a). Audiograms can only be released with the worker’s written consent.

Test results

The audiometric technician must give the worker a copy of the results of the audiogram. The worker is encouraged to keep a record of audiometric test results in case the worker develops a hearing loss. Because employers are only required to keep audiometric test results for 10 years, the worker needs to be responsible for documenting his or her hearing over the course of his or her working life.

If the results of the audiogram are abnormal, the audiometric technician must advise the worker of the test result and request the worker to provide a health history related to hearing. The audiometric technician must send the results of an abnormal audiogram or an audiogram showing an abnormal shift, the baseline audiogram, and the health history to the physician or audiologist designated by the employer to review audiograms.

Responsibility of designated physician and audiologist

The physician or audiologist designated by the employer reviews relevant medical information and the audiogram to ensure that the test results are valid. If the audiogram is valid, the physician or audiologist confirms the classification of the test results as being either an abnormal or an abnormal shift audiogram. The physician or audiologist can recommend follow-up which may include repeat testing or referral to another health care professional.

If the physician or audiologist confirms that the audiogram is an abnormal or an abnormal shift audiogram, the worker must be advised of this within 30 days of the physician or audiologist receiving the test results. With the worker’s written consent, the physician or audiologist must provide a copy of the audiometric test results to the worker’s physician.

The physician or audiologist must advise the employer as to the effectiveness of the noise management program in place at the work site as it relates to worker hearing. In order for the employer to evaluate the effectiveness of its program, the employer should also designate a knowledgeable person at the work site to consult with the physician or audiologist to provide specific details of the noise management program, such as hearing protection worn, work site noise levels, and personal dosimetry results. This person could be the audiometric technician.

When advising the employer as to the effectiveness of the noise management program, a list with the names of the workers and the dates when they were tested should be given to the employer, not the worker’s actual audiograms. Audiograms should be categorized and an explanation of the group results given to the employer. Analyzing audiometric test results can provide a good indication of the program’s effectiveness.

The audiometric technician or health professional must keep the audiogram and health history for at least 10 years.

Who pays for audiometric testing?

The employer is responsible for paying for audiometric testing and the interpretation of the results. Every effort should be made to have the audiometric testing conducted during normal working hours. If the testing takes place during the worker’s hours of work, the worker’s wages, salary or benefits cannot be deducted for the period of time the worker is being tested. If it is impractical for the worker to have the audiogram during his or her normal working hours, the employer must pay the worker for the time that is spent having the test conducted. If travel to or from the audiometric testing happens during working hours, the worker’s wages, salary or benefits cannot be deducted for this period.