Occupational noise monitoring is the first compliance step under OSHA 1910.95: it determines which employees require audiometric testing, what hearing protection is needed, and what records must be maintained. This guide covers the complete OSHA framework — when monitoring is required, what instruments meet the standard, how to conduct a survey, and how to interpret and document the results.
Soundtrace links frequency-specific ambient noise data to each individual audiogram event — providing event-level exposure documentation that goes beyond periodic area surveys and creates a stronger evidentiary record for OSHA compliance and WC defense.
Noise monitoring is required whenever there is information indicating any employee’s exposure may equal or exceed the action level. Any facility with significant machinery should monitor before assuming all exposures are safe.
When Monitoring Is Required
OSHA 1910.95(d)(1) requires monitoring when information indicates any employee’s exposure may equal or exceed 85 dBA TWA. Re-monitoring is required whenever a change in production, process, equipment, or controls may have increased exposures to the action level.
Approved Instruments and Settings
| Setting | OSHA Required Value | Why It Matters |
|---|---|---|
| Frequency weighting | A-weighting (dBA) | Correlates with hearing damage risk; required for OSHA compliance |
| Criterion level | 90 dBA | The PEL; dosimeter uses this as 100% dose reference |
| Threshold level | 80 dBA | Captures all noise contributing to action-level dose |
| Exchange rate | 5 dB | OSHA doubling rate (NIOSH uses 3 dB) |
| Response time | Slow | OSHA standard for continuous and intermittent noise |
| Dosimeter standard | ANSI S1.25 | Required instrument specification for personal dosimetry |
| SLM standard | ANSI S1.4 Type 2 minimum | Minimum accuracy grade for area survey instruments |
Monitoring Methods
Personal dosimetry is the preferred method for HCP enrollment decisions. The worker wears a dosimeter during a full representative shift, and the device automatically calculates TWA and dose. Area monitoring with a sound level meter maps noise levels at fixed locations. For workers with mobile roles or variable exposure, personal dosimetry is required.
Action Level vs. PEL
The action level (85 dBA TWA) triggers HCP enrollment. The PEL (90 dBA TWA) triggers mandatory HPD use and engineering or administrative controls. Workers between 85–90 dBA must be enrolled in the HCP but HPD use is voluntary unless they have a confirmed STS.
Required Actions After Monitoring
- Notify affected employees of their monitoring results
- Enroll workers at or above 85 dBA TWA in the hearing conservation program
- Implement engineering or administrative controls for workers at or above the PEL where feasible
- Require HPD use for all workers at or above the PEL
- Verify HPD adequacy using the derated NRR calculation
Recordkeeping Requirements
Noise exposure measurement records must be retained for at least 2 years. Records must include: monitoring method, instrument make/model/serial number, calibration records, individual employee results, and enrollment determinations. Best practice: retain noise monitoring records significantly beyond the OSHA minimum — WC claims can arrive 20–30 years after exposure.
Frequently asked questions
Noise data linked to every audiogram — not just periodic surveys
Soundtrace documents frequency-specific ambient noise levels at the time of each individual audiogram — creating event-level noise validation that goes beyond periodic area monitoring.
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