Introduction: At certain levels, noise exposure is harmful to the ear. Over a period of approximately thirty years (1968 to 2000), the IUMT in Lyon conducted audiometric follow-ups of workers in various sectors, as well as sound level measurements. Objective: The objective is to utilize these historical data on exposure to potentially harmful noise to develop an occupation-exposure matrix. Methods: The audiometric examination, conducted in a soundproof booth by experienced audiologists, was supplemented by an occupational questionnaire, exposure history, and ENT history. An analytical method based on the concept of average hearing loss at age 35 (PAM35) by Lafont and Duclos will enable a collective analysis of hearing loss to derive an estimate of a "theoretical" noise level within a group of workers. Available sound level measurements will also be used. Results: the data currently being analyzed cover approximately 600 companies representing various sectors of activity (agriculture, manufacturing, energy production, construction, transportation, education, healthcare, etc.). Approximately 70,000 audiometric records relating to various job positions (production workers and support staff) are available. For example, in an agri-food company, the theoretical exposure level is estimated at 90.1 dB(A) in 1990 and 87.5 dB(A) in 2000 based on analyses of 90 and 56 audiometric records, respectively. Conclusion: Using this database allows for a comparison of potential exposure to harmful noise across different jobs, as well as an analysis of how it has changed over time. This work represents a first step in the development of a job-noise exposure matrix. (R.A.°