The SOII is a cooperative Federal - State program in which employer reports are collected annually from a nationally representative sample of private industry establishments. The survey measures nonfatal injuries and illnesses only and excludes the self-employed, farms with fewer than 11 employees, private household workers, and employees in Federal government agencies. For the first time in 2008, the SOII provided national public sector estimates covering nearly 19 million state and local government workers.
Noise-induced hearing loss for recordkeeping purposes is a change in hearing threshold relative to the baseline audiogram of an average of 10 dB or more in either ear at 2000, 3000, and 4000 hertz and the employee's total hearing level is 25 decibels (dB) or more above the audiometric zero (also averaged at 2000, 3000, and 4000 hertz) in the same ear(s). The incidence rates represent the number of illnesses per 10,000 full-time workers and were calculated as: (N/EH) x 20,000,000, where N= number of illnesses, EH=total hours worked by all employees during the calendar year, and 20,000,000=base for 10,000 equivalent full-time workers (working 40 hours per week, 50 weeks per year. Information on the type of industry for the numerator is based on employer responses and converted to North American Industry Classification system (NAICS) codes.
Work-related noise-induced hearing loss continues to be a significant public health problem, accounting for nearly 10% of all recordable illnesses annually.