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Occupational noise monitoring is the process of measuring worker noise exposure to determine whether it meets or exceeds OSHA's action level (85 dBA TWA) or permissible exposure limit (90 dBA TWA). Under 29 CFR 1910.95(d), employers must conduct noise monitoring whenever noise exposure may equal or exceed the action level. This guide covers when monitoring is required, how it is conducted, which instruments OSHA accepts, and what employers must do with the results.
Soundtrace is a digital hearing conservation platform that integrates continuous noise monitoring with audiometric testing, STS detection, and cloud recordkeeping—so exposure data links directly to individual hearing records.
Under 1910.95(d)(1), employers must monitor noise exposure when information indicates that noise levels may equal or exceed the 85 dBA action level. OSHA does not require continuous monitoring of every worker—it requires monitoring whenever there is reason to believe the action level could be reached.
If workers must raise their voices to be understood at arm's length, ambient noise is likely above 85 dBA. This informal test is a reliable trigger for formal monitoring.
Published noise output specs for machinery, power tools, and production equipment often provide the first indication that formal monitoring is needed.
Reports of tinnitus, muffled hearing after shifts, or difficulty hearing speech are clinical indicators that exposure may be at or above the action level.
Previous noise surveys showing exposures near the action level must be re-evaluated after any change to equipment, production rate, or work area configuration.
Under 1910.95(d)(3), employers must re-monitor whenever a change in production, process, equipment, or controls may have increased noise exposure. Simply passing a prior survey is not a permanent exemption.
OSHA noise monitoring is not a one-time checkbox. Any significant change to equipment, production rate, or facility layout is a legal trigger for a new survey under 1910.95(d)(3).
OSHA 1910.95(d)(2)(i) specifies that monitoring must use either a sound level meter or a noise dosimeter that integrates noise over the work shift. Both instruments must meet ANSI S1.4 Type 2 specifications at minimum.
Best for: Area surveys, mapping noise zones, identifying high-noise equipment sources. Measures instantaneous or averaged noise levels at a fixed point. Must use A-weighting and slow response for general area monitoring.
Best for: Measuring individual worker TWA exposure across a full shift. Worn by the worker at the collar or lapel. Must use A-weighting, slow response, 80 dB threshold and 5 dB exchange rate per 1910.95 Appendix A.
Using dosimeters with incorrect settings produces exposure data that cannot be used for OSHA compliance determinations. Always verify instrument configuration before monitoring begins.
Use a sound level meter to map the facility. Identify areas where noise readings consistently exceed 80–85 dBA.
Choose the highest-exposed worker in each job classification in potentially overexposed areas.
Mount the microphone at the collar on the dominant-noise side. Worker performs normal full-shift tasks.
Retrieve TWA, dose percentage, and peak levels. Compare against 85 dBA action level and 90 dBA PEL.
Under 1910.95(e), workers must be notified of results. Enroll at-risk workers in the HCP and implement controls where the PEL is exceeded.
Triggers enrollment in the HCP: audiometric testing, HPD provision, and training. Does NOT automatically require engineering controls.
Triggers requirement to implement engineering and administrative controls. HPD cannot substitute for controls when feasible controls exist.
Reaching the action level triggers the full HCP. Reaching the PEL triggers the additional obligation to implement engineering or administrative controls to actually reduce noise exposure.
Under 1910.95(e), all monitored employees must receive their individual results promptly.
Workers at or above 85 dBA TWA must receive audiometric testing, HPDs, and annual training.
If exposure exceeds 90 dBA PEL, feasible engineering and administrative controls must be implemented.
Retain noise monitoring records, calibration logs, and worker notifications for at least 2 years per 1910.95(m)(3).
Re-monitor after any change to equipment, production, or controls that may have increased exposures.
If new classifications are found at or above the action level, enroll all workers in that classification.
Under 1910.95(m)(3), noise exposure measurement records must be retained for at least 2 years. Records must include the date, instruments used with serial numbers, calibration documentation, names and job classifications of workers monitored, and TWA results.
Soundtrace combines continuous area monitoring with personal dosimetry data, automatic enrollment triggers, and linked audiometric records—all in one platform.
Book a DemoGet a quote for your facility →Under 29 CFR 1910.95(d)(1), employers must monitor noise when information indicates that noise levels may equal or exceed the 85 dBA action level. Triggers include equipment noise levels, worker complaints, or communication difficulty. Monitoring must be repeated after any change that may increase exposure under 1910.95(d)(3).
OSHA allows sound level meters and personal noise dosimeters meeting ANSI S1.4 Type 2 minimum specifications. Dosimeters must use 80 dBA threshold, 90 dBA criterion level, 5 dB exchange rate, A-weighting, and slow response for OSHA-compliant TWA results.
The action level (85 dBA TWA) triggers the full HCP. The PEL (90 dBA TWA) additionally triggers engineering and administrative controls to reduce noise exposure. Reaching the action level does not require engineering controls; exceeding the PEL does.
Under 1910.95(m)(3), noise exposure measurement records must be retained for at least 2 years. Records must include measurement dates, instruments with serial numbers, calibration data, and names and job classifications of workers monitored.