30 CFR §62.172
Evaluation of audiograms
(a) The mine operator must:
(1) inform persons evaluating audiograms of the requirements of this part and provide those persons with a copy of the miner's audiometric test records;
(2) have a physician or an audiologist, or a qualified technician who is under the direction or supervision of a physician or audiologist:
(i) determine if the audiogram is valid; and
(ii) determine if a standard threshold shift or a reportable hearing loss, as defined in this part, has occurred.
(3) instruct the physician, audiologist, or qualified technician not to reveal to the mine operator, without the written consent of the miner, any specific findings or diagnoses unrelated to the miner's hearing loss due to occupational noise or the wearing of hearing protectors; and
(4) obtain the results and the interpretation of the results of audiograms conducted under this part within 30 calendar days of conducting the audiogram.
(b)(1) The mine operator must provide an audiometric retest within 30 calendar days of receiving a determination that an audiogram is invalid, provided any medical pathology has improved to the point that a valid audiogram may be obtained.
(2) If an annual audiogram demonstrates that the miner has incurred a standard threshold shift or reportable hearing loss, the mine operator may provide one retest within 30 calendar days of receiving the results of the audiogram and may use the results of the retest as the annual audiogram.
(c) In determining whether a standard threshold shift or reportable hearing loss has occurred, allowance may be made for the contribution of aging (presbycusis) to the change in hearing level. The baseline, or the revised baseline as appropriate, and the annual audiograms used in making the determination should be adjusted according to the following procedure:
(1) Determine from Tables 62-3 or 62-4 the age correction values for the miner by:
(i) Finding the age at which the baseline audiogram or revised baseline audiogram, as appropriate, was taken, and recording the corresponding values of age corrections at 2000, 3000, and 4000 Hz;
(ii) Finding the age at which the most recent annual audiogram was obtained and recording the corresponding values of age corrections at 2000, 3000, and 4000 Hz; and
(iii) Subtracting the values determined in paragraph (c)(1)(i) of this section from the values determined in paragraph (c)(1)(ii) of this section. The differences calculated represent that portion of the change in hearing that may be due to aging.
(2) Subtract the values determined in paragraph (c)(1)(iii) of this section from the hearing threshold levels found in the annual audiogram to obtain the adjusted annual audiogram hearing threshold levels.
the hearing threshold levels in the baseline audiogram or revised baseline
audiogram from the adjusted annual audiogram hearing threshold levels determined
in paragraph (c)(2) of this section to obtain the age-corrected threshold