Testing alone is not a preventive mechanism but it is an important part of managing risks from noise exposure in a workplace.
The hearing of workers exposed to noise can be monitored through regular audiometric tests. Testing is an important part of a hearing conservation program to manage risks from noise exposure in a workplace. Any changes in a person's hearing levels revealed by audiometric testing should be investigated as to their cause(s) and the need for corrective action.
Audiometric testing should also be provided to workers exposed to acoustic shock in call centres or to workplace ototoxins (chemicals that may either alone, or when combined with noise, result in hearing loss).
All testing should be done by an appropriately trained and experienced person, using procedures and equipment that comply with Part 4: Auditory assessment of AS/NZS 1269: Occupational noise management.
Testing should include:
- an initial audiometric test carried out within three months of commencing work
- monitoring audiometric testing carried out within 24 months of the initial test for comparison of hearing abilities
- follow up monitoring audiometric testing every two years, if no threshold shift has been detected. High risk groups may require more frequent testing.
Threshold shifts in hearing
On exposure to noise above an intensity level of 75 dB(A), the ear's sensitivity level will decrease. This process is referred to as a shift in the threshold of hearing. The shift can be:
- temporary, called temporary threshold shift (TTS), and recovers gradually after the noise exposure
- permanent, called permanent threshold shift (PTS), and does not recover, resulting in permanent hearing loss.
Actions to be taken
If workers are found to have sufficient hearing loss to interfere with the safe performance of their jobs and their communication ability:
- all practicable steps should be taken to modify the work environment
- workers should be offered alternative work that does not put them at risk from excessive noise.
When temporary or permanent threshold shifts are revealed by audiometric tests or new tinnitus reported, action should be taken to inform the responsible person (or employer) to arrange to:
- review the worker's job to identify any changes that may have caused an increase in exposure to noise
- re-determine the worker's exposure to noise, if necessary
- check whether anything can be done to reduce the levels of noise to which the worker is exposed and the duration of exposure
- check the wearing conditions and rating of the worker's hearing protector to ensure it is adequate for the level of exposure to noise
- examine the hearing protector carefully and ensure it is not worn or damaged
- check the worker is able to fit the hearing protector properly
- check the hearing protector fits the worker closely and there are no leakage paths
- ask the worker if they have any difficulty in using the hearing protector
- check the worker actually uses the hearing protector correctly
- deal with any problems revealed by the above procedures, calling in expert advice as necessary
- notify WHSQ of an incident (if a significant permanent threshold shift due to excessive exposure to noise is revealed).
For more information on audiometric testing, you can download the Managing Noise and Preventing Hearing Loss Code of Practice 2011 (PDF, 1.24 MB).