Assessment of Workplace Noise

131

13.11 Hearing Conservation

The aim in introducing hearing conservation programmes in industry is to prevent occupational hearing loss by ensuring the assessment and control of exposure to excessive workplace noise. This can be achieved by programmes that incorporate the following essential features.

13.11.1 Assessment of Workplace Noise

The primary interest as far as workplace noise is concerned is with occupational noise exposure and compliance with an occupational noise exposure limit. Therefore a noise survey should be undertaken in areas where it is suspected that persons could be exposed to workplace noise in excess of the noise exposure limit, i.e. the First Action Level in EC member countries. In workplaces where the noise levels are reasonably constant, the survey should establish a noise level contour map, the typical full shift individual noise exposures for the jobs concerned, or both. Although compliance with the noise exposure limit is the primary concern, it is often easier, from an administrative point of view, for this to be achieved by specifying and ensuring compliance with a work area limit that is numerically equal to the noise exposure limit. Hence the contour approach. Three circumstances could prevail:  If only the contour approach is adopted, locations where the noise level is numerically equal to or greater than the noise exposure limit should be designated clearly, e.g. as Noise Hazard Areas. No person should be permitted to enter these areas without wearing suitable hearing protection irrespective of the duration of stay.  If the typical full shift individual noise exposures are determined, these should be compared with the noise exposure limit. For those jobs for which the limit is normally expected to be exceeded, suitable hearing protection should be worn in areas where high noise levels prevail.  If both a noise contour map and noise exposure data are obtained, a noise level numerically higher than the noise exposure limit may be 132 used for defining designated areas, provided it can be shown that the noise exposures are consistently below the noise exposure limit. Noise levels may be determined using a simple sound level meter Type 1 or Type 2, but it is essential that the instrument is used correctly if meaningful data are to be obtained, e.g. attention to calibration, account taken of type of noise, etc. In workplaces where the noise levels fluctuate e.g. workshop areas the survey should establish the typical full shift individual noise exposures for the jobs concerned for comparison with the noise exposure limit. For those jobs or job elements for which the limit is normally expected to be exceeded, suitable hearing protection should be worn. Apart from checking compliance with an exposure criterion, noise exposure measurements are also useful for indicating priority areas for noise control, for highlighting those personnel most at risk, and for hearing conservation education purposes.

13.11.2 Control of Workplace Noise