Audiogram classification is crucial for hearing protection of workers occupationally exposed to noise. The methods that have been proposed are based on two principles: the morphological evaluation of the audiometric curve (eg. Merluzzi-Pira-Bosio--MPB) or the average hearing loss on different frequencies (eg. Albera-Beatrice--AB). The purpose of this study was to classify audiograms compatible with chronic acoustic trauma performed at the Occupational Medicine Outpatient Clinic of CTO Hospital in Turin from 2004 to 2011 with the methods outlined in Guidelines published by SIMLII. A substantial agreement among the methods was observed. While MPB is the most appropriate method for secondary prevention, the AB would seem more appropriate for the verification of a permanent weakening that has to be reported to the competent legal authorities.