AS NZS 1269.4:2014 pdf free download – Occupational noise management
7.1 General
Audiometric testing shall be made available to all persons likely to be exposed to noise above the noise exposure criteria as set by the relevant statutory authorities or by the organization’s noise policy, whichever is the lower, or ototoxic agents as listed in Appendix C of AS/NZS 1269.0:2005. The test subject should be made fully aware of the reason why audiometry is being made available. One purpose of audiometry is to inform test subjects of any changes in their pure-tone thresholds. Audiometry is desirable because there are uncertainties in occupational noise management programs, e.g. error in noise exposure measurements and variability in the effectiveness of hearing protectors. Audiometry may assist in the early detection of inadequacies in the occupational noise management program and therefore enables early remedial action to be taken. Where audiometric testing is carried out it shall be in accordance with the requirements concerning audiometers, audiometric test environments and audiometric test procedures of this Standard. It shall be the responsibility of a particular individual within an organization to manage the audiometric program. The purpose of audiometry is to determine the test subject’s hearing threshold levels as accurately as practicable. Reference audiometry is used to establish the status of the test subject’s hearing thresholds, while monitoring audiometry is used to establish any subsequent deviations from that reference. The results of audiometry are influenced by learning, practice and motivation. It is therefore important to give the test subject sufficient practice in carrying out the tasks of audiometry and to encourage positive motivation towards the test before reference audiometry is performed.
The test-retest variability of audiometric results can be reduced by averaging thresholds across adjacent frequencies. Three is the optimum number of frequencies to include in the average. Audiometric test results are also influenced by the placement of the headphones on the subject’s head. Relative to the accuracy of single audiograms, the accuracy of audiometric data is greatly improved by recording the average of two or more audiograms, the headphones being completely removed and refitted on the subject between tests. The attendance of test subjects for periodic monitoring audiometry provides a useful opportunity to examine the condition of hearing protectors and to ensure that they are being worn correctly. Test subjects should therefore be requested to bring their hearing protectors with them whenever they have their hearing tested. The occurrence of tinnitus in noise-exposed people may be an early sign of noise-induced damage to the inner ear. The onset of noise-induced tinnitus often occurs early in the careers of noise-exposed people and may precede measurable effects on threshold sensitivity. The presence or absence of tinnitus shall therefore be recorded when audiometry is carried out and, if new tinnitus is present, appropriate action shall be taken (see Clause 9.4). The test subject and the tester should be comfortably seated during audiometric testing and should not be disturbed or distracted by events unrelated to the test procedure or by people in the surroundings. If manual audiometry is employed the subject shall be clearly visible to the tester but shall not be able to see or hear when the audiometer settings are being changed or the test tone is switched on or interrupted.