OSHA requires a hearing conservation program (29 CFR 1910.95) when workers are exposed to 85 dBA time-weighted average (TWA) or above. Program elements include: noise exposure monitoring, audiometric testing (baseline within 6 months, annual thereafter), hearing protection devices provided at no cost, employee training on noise hazards and protection, and recordkeeping. A Standard Threshold Shift (STS) of 10 dB or more averaged at 2000, 3000, and 4000 Hz triggers additional employer action.