The assessment of permaennt impairment for noise induced hearing loss claims can be found in Chapter 5.3.7 [2] of this handbook.
Links
[1] https://clik.dva.gov.au/user/login?destination=node/20893%23comment-form
[2] https://clik.dva.gov.au/military-compensation-srca-manuals-and-resources-library/permanent-impairment-handbook/ch-5-calculation-using-approved-guide/53-tables-1-13-approved-guide/537-ear-nose-and-throat-disorders-table-7