Noise and Hearing Conservation: OSHA Requirements

Occupational noise-induced hearing loss affects millions of workers and is entirely irreversible. Unlike many workplace injuries, the damage accumulates gradually over years without an obvious incident — workers often don't recognize the loss until it significantly affects their daily life. OSHA's hearing conservation standard (29 CFR 1910.95) applies to general industry workplaces where workers are exposed to high noise levels and creates a tiered set of obligations based on measured exposure.

The Two Thresholds

The standard establishes two key exposure levels, both measured as an 8-hour time-weighted average (TWA):

The action level triggers the hearing conservation program. The PEL triggers the additional obligation to implement engineering and administrative controls where feasible, not just provide hearing protection. At and above the PEL, hearing protection is a supplementary measure — not a substitute for controlling noise at the source.

How Noise is Measured

Noise exposure is measured in A-weighted decibels (dBA) — a measurement scale that approximates how the human ear perceives sound. The standard uses a 5 dB exchange rate, meaning that for every 5 dB increase in noise level, the permissible exposure time is halved:

Workers who are exposed to different noise levels throughout the day accumulate a "dose." If their combined dose across the workday reaches 100%, they've hit the PEL. If it reaches 50%, they've hit the action level.

Noise Monitoring

When there is reason to believe workers may be exposed at or above the action level, employers must conduct noise monitoring. This is typically done with a sound level meter (for spot measurements) or a personal noise dosimeter (worn by the worker to measure actual exposure over the shift).

Monitoring must be repeated when changes in production, process, or controls may have changed exposure levels. Workers must be notified of the results of noise monitoring and must be allowed to observe monitoring procedures.

If monitoring shows exposures at or above the action level, the employer must identify which workers are exposed and enroll them in the hearing conservation program.

Hearing Conservation Program Requirements

A hearing conservation program is required for all workers exposed at or above the action level (85 dBA TWA). The program must include all five of these elements:

1. Audiometric Testing

Workers exposed at or above the action level must receive audiometric testing — a baseline hearing test followed by annual monitoring tests. The purpose is to detect early hearing loss before it becomes significant.

• Baseline audiogram: Must be conducted within 6 months of the worker's first exposure at or above the action level. The baseline establishes the comparison point for all future tests.
• Annual audiogram: Conducted each year for all enrolled workers. Results are compared to the baseline to identify standard threshold shifts (STS) — a change of 10 dB or more averaged across 2,000, 3,000, and 4,000 Hz in either ear.
• If an STS is identified, the employer must: fit the employee with hearing protectors or upgrade existing protection, require use, and if the STS is work-related, record it on the OSHA 300 log.
• Audiometric testing must be provided at no cost to the worker.

2. Hearing Protectors

Hearing protectors must be made available to all workers exposed at or above the action level — at no cost. Workers must have a choice of hearing protectors from at least one type of plug and one type of muff. Workers exposed above the PEL, or who have experienced an STS, must use hearing protection.

Selecting adequate hearing protection: The hearing protector's noise reduction rating (NRR) must be sufficient to reduce the worker's exposure to below the action level. OSHA requires applying a correction factor — derating the NRR by 50% for earmuffs, or using the formula: (NRR - 7) / 2 for earplugs. This accounts for real-world fit that falls short of laboratory conditions.

Hearing protectors must be replaced as necessary and kept clean. Workers must be trained on correct insertion (for plugs) and proper fit (for muffs).

3. Training

Annual training is required for all workers enrolled in the hearing conservation program. Training must cover:

• The effects of noise on hearing
• The purpose of hearing protectors, including advantages, disadvantages, and attenuation of various types
• Instructions on selection, fitting, use, and care of hearing protectors
• The purpose of audiometric testing and the audiometric test procedures

4. Recordkeeping

Employers must maintain records of:

• Noise exposure measurements — retained for 2 years
• Audiometric test records — retained for the duration of the worker's employment

Audiometric test records must include: the name and job classification of the employee, the date of the audiogram, the examiner's name, the date of the last acoustic or exhaustive calibration of the audiometer, and the employee's most recent noise exposure assessment.

5. Monitoring Results Notification

Workers must be notified of the results of noise monitoring. If they experience a standard threshold shift, they must be notified within 21 days.

Engineering and Administrative Controls

When exposures equal or exceed the PEL (90 dBA), feasible engineering and administrative controls must be used to reduce exposure, even if hearing protection is also provided. Engineering controls are modifications to the equipment or environment — enclosures, damping, isolation, substitution of quieter equipment. Administrative controls are changes to work practices — limiting exposure time, rotating workers, scheduling noisy operations when fewer workers are present.

OSHA does not require engineering controls to be implemented if they are not feasible — but "not feasible" must be demonstrable. Simply preferring hearing protection as the easier solution is not sufficient justification for not implementing available engineering controls.

Is Your Workplace Loud Enough to Matter?

A simple field test: if you have to raise your voice to be understood by someone standing 3 feet away, the noise level is probably at or above 85 dBA. Common sources of workplace noise at relevant levels include:

• Pneumatic tools: 90–110 dBA
• Grinding equipment: 85–100 dBA
• Packaging machinery: 85–95 dBA
• Printing equipment: 85–100 dBA
• Woodworking machinery: 85–110 dBA
• Metal stamping: 95–110 dBA
• Chainsaws and jackhammers: 100–115 dBA

If any of these are present in your workplace, noise monitoring is likely warranted to determine actual worker exposure levels.

Common Violations