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The November 2023 Change 1 to DoD Instruction 6055.12 introduced the most operationally significant new hearing conservation requirement in recent DoD history: mandatory Personal Attenuation Rating (PAR) fit testing for all service members and DoD civilian employees with documented noise exposures exceeding 95 dBA 8-hour TWA. This guide explains what the requirement is, who it applies to, what PAR testing actually measures, how it differs from the OSHA baseline, and what safety managers need to know about implementation.
Soundtrace supports DoD civilian organizations with automated in-house audiometric testing and professional supervisor oversight that satisfies both the 29 CFR 1910.95 baseline and DoDI 6055.12's expanded hearing conservation requirements, including awareness of the 2023 fit-testing mandate for qualifying workers.
DoDI 6055.12 Change 1 (November 22, 2023): All service members and DoD civilian employees with documented noise exposures exceeding 95 dBA 8-hour TWA must receive initial hearing protector fit testing using PAR methodology — going beyond what OSHA 1910.95 requires.
DoDI 6055.12 was most recently reissued in August 2019. Change 1, issued November 22, 2023, made one substantive operational addition: the mandatory PAR fit-testing requirement. This was not a clarification or administrative update — it created a new program element that hadn't existed in the prior version of the instruction.
Prior to Change 1, DoDI 6055.12 — like OSHA 1910.95 — required that hearing protectors provide adequate attenuation for the worker's actual noise exposure, based on NRR de-rating methods. Change 1 adds a direct measurement requirement for the highest-exposed workers: rather than estimating protection through NRR de-rating, workers with documented exposures above 95 dBA TWA must now be individually fit tested to confirm their specific device is delivering adequate protection.
Personal Attenuation Rating (PAR) testing measures the actual noise reduction achieved by a specific hearing protector on a specific individual during a specific fitting:
The word "personal" in PAR is the key distinction. NRR represents a population average from laboratory testing. PAR represents this person, today, wearing this device this way. A worker who achieves a PAR of 12 dB with their issued earplugs may have an NRR de-rated value suggesting 15–20 dB of protection. The gap is real, and for workers above 95 dBA TWA, it's the difference between adequate and inadequate protection.
| Dimension | NRR De-Rating (OSHA 1910.95 Baseline) | PAR Fit Testing (DoDI 6055.12, 2023) |
|---|---|---|
| What is measured | Population-average attenuation from manufacturer testing, de-rated for field use | Actual attenuation for this individual wearing this device at this fitting |
| Individual variation captured | No — assumes all workers achieve the population average | Yes — directly measured; poor fit is immediately visible in the score |
| Effect of anatomy | Not captured — ear canal shape, beard, glasses not accounted for | Fully captured — all physical factors affecting seal are reflected in PAR score |
| Training benefit | None inherent — no feedback on how well device is worn | Immediate — worker sees score improve as fitting technique improves |
| Documentation value | Attenuation adequacy recorded based on NRR calculation | Per-employee, per-device PAR score on record; stronger evidence of actual protection |
| Who it applies to under DoDI | All noise-exposed workers at or above 85 dBA TWA action level | Workers with documented exposure above 95 dBA TWA |
| Required by OSHA 1910.95 | Yes — Appendix B methods for adequacy determination | No — PAR exceeds the OSHA baseline |
| Required by DoDI 6055.12 | Yes — still required for workers below 95 dBA TWA | Yes — required for workers above 95 dBA TWA (Change 1, November 2023) |
The fit-testing requirement is triggered by documented exposure exceeding 95 dBA TWA. Noise monitoring is a prerequisite — you cannot determine who requires PAR fit testing without knowing who has exposures above the threshold. Installations with outdated noise surveys for high-noise work areas may have a documentation gap that prevents proper implementation of Change 1.
For workers above 95 dBA TWA, hearing protection is the primary control measure. Engineering controls are often not feasible at these levels (aircraft maintenance, artillery, heavy industrial). Confirming that HPDs are actually delivering adequate attenuation — not just that the NRR calculation suggests they should — directly reduces the risk of progressive hearing loss in the highest-exposure population.
When workers see their PAR score improve as they adjust their device, they learn what proper fit actually means in a way classroom instruction cannot replicate. Workers who have been fit tested consistently show improved compliance with correct use in the field.
A documented PAR score is stronger evidence of adequate protection than an NRR de-rating calculation. In workers' compensation or VA disability proceedings involving a worker in the HCP, PAR records provide direct evidence of the actual protection level provided — relevant to causation and liability.
As of 2025, the Defense Centers for Public Health – Aberdeen is conducting implementation studies across military installations. DHA is working to establish equipment procurement pathways and technician training programs.
The 2023 Change 1 applies to DoD civilian employees with the same force as it applies to military personnel. This creates a compliance obligation for civilian HCP managers with no equivalent in the private sector under OSHA 1910.95:
PAR (Personal Attenuation Rating) testing measures the actual noise reduction achieved by a specific hearing protector on a specific individual. A portable system measures sound levels inside and outside the ear with the device worn, yielding a real protection score for this person with this device — not a population-average estimate from the NRR label.
All service members and DoD civilian employees with documented noise exposures exceeding 95 dBA 8-hour TWA enrolled in the hearing program. Workers with exposures below the 95 dBA TWA threshold continue with NRR adequacy estimation. Defense contractors are not subject to the DoDI requirement.
No. OSHA 1910.95 requires only that hearing protectors provide adequate attenuation using NRR de-rating methods. PAR fit testing is not required by OSHA and exceeds the OSHA baseline. It is currently required only by DoDI 6055.12 Change 1 for DoD personnel with documented exposures above 95 dBA TWA.
As of 2025, DCPH-A is conducting implementation studies across installations and DHA is developing equipment procurement pathways and technician training. Installation HROs should contact their DHA Public Health representative for current guidance and timelines specific to their installation.
If a worker's PAR score indicates insufficient attenuation for their exposure level, the device, fitting technique, or both must be changed until adequate protection is confirmed. The process is a training opportunity — workers learn what correct fit looks and feels like, improving real-world use compliance.
NRR de-rating uses a population-average laboratory rating with a correction factor. PAR measures actual attenuation for this person with this device at this fitting — capturing anatomy, hair, glasses, beard, and technique. Workers who appear adequately protected by NRR calculation may score below adequate protection on PAR testing.
Soundtrace supports DoD civilian safety managers with automated in-house audiometric testing, audiologist review on every record, and documentation satisfying both OSHA 1910.95 and DoDI 6055.12 requirements — including awareness of the 2023 PAR fit-testing mandate for qualifying workers.
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