An employer or self-employed person shall ensure that the exposure of a person to noise is either prevented or, where this is not reasonably practicable, adequately controlled: Provided that the control of the exposure shall be regarded as adequate if the exposure is below the noise-rating limit, or if the exposure is at or above the noise rating
limit but the reason has been identified and action is taken as soon as is reasonably practicable, by means other than the use of hearing protective equipment, to lower exposure so that it does not exceed the noise-rating limit.