Z107.56-94 (R2004)

Scope 1.1 This Standard describes procedures for the determination of the occupational noise exposure level (L ex,T) using sampling techniques. L ex,T represents the long-term noise exposure of employees. It is calculated from measurements of the equivalent sound level (L eq,t) in the workplace. The procedures in this Standard normally form part of any occupational hearing conservation program. The user of this Standard should be proficient in noise measurement. 1.2 This Standard provides procedures for measuring the occupational noise exposure from all types of noise, eg, continuous noise, pure tones, and impulse noise. All types of noise (including impulse noise) are measured in terms of equal energy. 1.3 This Standard can be used for determination of the nosie exposure level of individuals (L ex,T) or extended to groups (L TRADE) with similar noise exposures. It can also be used to measure the noise exposure (L eq,t) from a given job or activity (eg, operating a particular machine). 1.4 This Standard provides for measurements in terms of L eq,t (3 dB exchange rate) and calculation of (L ex,T). Procedures for calculating related quantities, such as Pa2h, are provided. This Standard may also be used for the measurement of L OSHA (5 dB exchange rate) and calculation of associated indices as shown in Appendix D. In this case, the results may not be a good representation of exposure to impulsive noise. Note: Measurements taken in L eq cannot be converted to L OSHA, or vice versa, unless the time distribution of sound levels is known. 1.5 This Standard provides procedures to determine the noise exposure level of employees with a given precision. In certain cases, the user is only interested in determining that an employee's exposure is above or below the criterion level. The procedures in this Standard can be relaxed in this case when the noise exposure level is either far above or far below the criterion level.