A hearing conservation program is required whenever employees are exposed to noise at or above 85 decibels averaged over an eight-hour workday. This threshold, called the “action level,” is set by OSHA’s general industry noise standard (29 CFR 1910.95) and applies regardless of whether workers wear hearing protection. If monitoring shows any employee hits that 85 dBA time-weighted average, the employer must implement a full program that includes monitoring, hearing tests, protective equipment, and training.
The 85 dBA Action Level vs. the 90 dBA Exposure Limit
OSHA uses two distinct noise thresholds, and the difference matters. The action level of 85 dBA triggers the hearing conservation program. The permissible exposure limit (PEL) of 90 dBA is the maximum allowable exposure for an eight-hour shift. When noise exceeds the PEL, employers must take additional steps to reduce the noise itself through engineering or administrative controls, not just protect workers’ hearing.
Both thresholds use a 5 dB exchange rate. That means for every 5 dB increase above the limit, the allowable exposure time is cut in half. At 95 dBA, for example, the permitted duration drops to four hours. At 100 dBA, it drops to two hours. This exchange rate is more lenient than what NIOSH recommends. NIOSH set its own recommended exposure limit at 85 dBA with a 3 dB exchange rate, meaning the allowable time halves with every 3 dB increase. NIOSH’s approach is stricter and reflects more current science, but OSHA’s standard is the one that carries legal enforcement.
What the Program Must Include
Once noise exposure reaches the action level, OSHA requires employers to put several components in place. These aren’t optional add-ons; each one is a regulatory requirement.
- Noise monitoring: Employers must measure workplace noise levels to identify which employees are at or above 85 dBA. These measurements must be repeated whenever changes in production, equipment, or processes could raise exposure levels.
- Audiometric testing: Every exposed worker needs a baseline hearing test, followed by annual hearing tests to track changes over time.
- Hearing protection: Employers must provide hearing protectors at no cost to all workers exposed at or above 85 dBA. Workers exposed above the 90 dBA PEL must wear them.
- Training: Employees need annual training on the effects of noise, the purpose of hearing protectors, and the purpose of audiometric testing.
- Recordkeeping: Noise exposure measurements must be kept for at least two years. Audiometric test records must be retained for the entire duration of the employee’s employment.
Audiometric Testing Timelines
The baseline audiogram must be completed within six months of the employee’s first exposure at or above 85 dBA. There is one exception: employers who use mobile testing vans get up to one year to establish the baseline. During the gap between first exposure and baseline testing, the employee must be fitted with and required to wear hearing protection.
After the baseline is set, every exposed worker needs a new audiogram at least once a year. These annual results are compared against the baseline to detect any shifts in hearing ability. If testing reveals a standard threshold shift, which is an average decline of 10 decibels or more at the 2000, 3000, and 4000 Hz frequencies in either ear, the employer must take action. That includes refitting or replacing hearing protectors, ensuring the protection reduces exposure to at least 85 dBA, and notifying the employee in writing within 21 days.
Construction vs. General Industry
The rules differ depending on your industry, and the gap is significant. General industry employers (manufacturing, warehousing, utilities, etc.) must start a hearing conservation program at 85 dBA. Construction employers operate under a separate standard (29 CFR 1926.52) that only requires a hearing conservation program when noise exceeds the PEL of 90 dBA. The construction standard also lacks many of the detailed requirements found in the general industry rule, including specific audiometric testing schedules and training mandates.
In practice, this means construction workers can be exposed to noise levels between 85 and 90 dBA without the same protections that general industry workers receive. OSHA has acknowledged this gap but has not updated the construction noise standard to match.
How Hearing Protector Adequacy Is Measured
Simply handing out earplugs doesn’t satisfy the requirement. Employers need to verify that the hearing protection they provide actually reduces noise to safe levels. This is done using the noise reduction rating (NRR) printed on the protector’s packaging.
The calculation depends on how noise was measured. If the workplace measurement was taken using C-weighting, you subtract the NRR directly from the measured level. If the measurement used A-weighting (the more common method), you subtract 7 dB from the NRR first, then subtract the result from the measured noise level. So a protector rated at NRR 29 used in a workplace measured at 95 dBA (A-weighted) would provide an estimated exposure of 95 minus (29 minus 7), or 73 dBA under the protector.
For workers who have already experienced a standard threshold shift, the employer must ensure that hearing protection brings their exposure down to at least 85 dBA. For all other workers exposed above the PEL, protectors must reduce exposure to below 90 dBA.
Who Conducts the Testing and Monitoring
Audiometric testing must be performed by a licensed or certified audiologist, a physician, or a technician who is certified by the Council of Accreditation in Occupational Hearing Conservation or who has satisfactorily demonstrated competence. A physician or audiologist must review any problem audiograms. Noise monitoring can be performed by the employer or a contracted industrial hygienist, but the equipment must be calibrated and the methodology must follow OSHA’s specifications.
Employers are required to notify each employee of their individual monitoring results and allow employees to observe any noise measurements being taken. All audiometric test results must be made available to the affected employee.