A. The "Guides to the Evaluation of Permanent Impairment" of the American Medical Association, or any alternative method approved pursuant to 85 O.S., Section 333(C) that deviates from or is used in place of or in combination with the Guides, in effect on the date of injury, shall be used to evaluate permanent impairment caused by hearing loss where the last exposure occurred on or after August 26, 2011. Objective medical evidence necessary to prove physical or anatomical impairment in occupational