9.1.1. This chapter gives additional and specific information to help employers,
workers and competent authorities apply the general principles in Chapters 2 and 3.
9.1.2. The information on the assessment of noise exposure and protective and
preventive measures contained in this code and provided for in the Working
Environment (Air Pollution, Noise and Vibration) Convention (No. 148), and
Recommendation (No. 156), 1977, and the ILO code of practice Protection of workers
against noise and vibration in the working environment (Geneva, 1984) should apply.
Further detailed information can be found in section 9 of the annex.
9.1.3. In addition, for the prediction of the amount of hearing loss expected to
occur as a function of noise exposure level and duration, age and sex, when no national
provisions are available, then the international consensus standard ISO 1999, Acoustics:
Determination of occupational noise exposure and estimate of noise-induced hearing
impairment (1990), should apply.
9.1.4. This chapter does not deal with exposure to either infra-sound or
ultrasound. Other national or internationally recognized standards should be consulted
for an assessment of the hazard or risk from exposure to those types of sound.
9.2.1. The level of noise and/or duration of exposure should not exceed the
limits established by the competent authority or other internationally recognized
standards. The assessment should, as appropriate, consider:
(a) the risk of hearing impairment;
(b) the degree of interference to speech communications essential for safety purposes;
(c) the risk of nervous fatigue, with due consideration to the mental and physical
workload and other non-auditory hazards or effects.
9.2.2. For the prevention of adverse effects of noise on workers, employers
(a) identify the sources of noise and the tasks which give rise to exposure;
(b) seek the advice of the competent authority and/or the occupational health service
about exposure limits and other standards to be applied;
(c) seek the advice of the supplier of processes and equipment about expected noise