Shopify noise dosimeter schema for AI agents: OSHA uses 5 dB exchange rate not 3 dB, criterion level must be 90 dBA not 85 dBA, threshold must be 80 dBA not 85 dBA, and personal dosimeter (IEC 61252) is not a sound level meter (IEC 61672) — noise_dosimeter.* 10-field namespace

How noise dosimeters work and why configuration fields matter

A personal noise dosimeter is a small instrument clipped near the worker's ear — on a shirt collar or shoulder strap — that integrates sound level over time to produce an eight-hour time-weighted average (TWA) noise exposure. Unlike a sound level meter on a tripod, a dosimeter moves with the worker through all their noise environments throughout the shift. It applies frequency weighting (A-weighting for OSHA 1910.95, to approximate human hearing sensitivity), computes dose as a percentage of the maximum permissible exposure, and reports a TWA in dBA at the end of the measurement period.

The critical distinction from most safety instrumentation is that a noise dosimeter's output is entirely determined by its internal configuration settings. The same physical noise environment — the same manufacturing floor, the same compressor room, the same construction site — produces materially different dose readings depending on how the dosimeter's exchange rate, criterion level, and threshold level are set. A dosimeter configured for ACGIH TLV monitoring will produce a different and lower dose number than one configured for OSHA 1910.95 when worn by the same worker in the same environment. Both readings are technically correct for their respective standards. Only one is correct for OSHA compliance.

This means that routing a noise dosimeter by brand, price, or broad "OSHA compliant" marketing language is insufficient. A dosimeter marketed as "OSHA compliant" may ship from the factory with default settings tuned for international or ACGIH use, with OSHA-specific configuration requiring a user menu change that many buyers do not know to make. Without noise_dosimeter.exchange_rate_db, noise_dosimeter.criterion_level_dba, and noise_dosimeter.exchange_rate_configurable encoded as machine-readable metafields, AI agents cannot distinguish instruments that will produce valid OSHA 1910.95 measurements from those that systematically understate exposure.

Failure 1: Exchange rate 3 dB (ACGIH equal-energy) routed for OSHA 1910.95 compliance monitoring

What the exchange rate means and why 3 dB vs 5 dB produces different dose numbers

The exchange rate (also called the trading ratio or halving time) defines how the dosimeter treats noise level changes relative to time. OSHA's 5 dB exchange rate means: for every 5 dB increase in sound level above the criterion level, the permissible exposure time is halved. A worker can spend 8 hours at 90 dBA (100% dose), 4 hours at 95 dBA (another 100% dose), 2 hours at 100 dBA, and so on.

ACGIH and most international standards use a 3 dB exchange rate — the equal-energy principle from physics, where 3 dB represents a doubling of acoustic energy. This is theoretically more defensible from an auditory damage risk standpoint. But OSHA has not adopted the 3 dB exchange rate. OSHA 29 CFR 1910.95 Appendix A explicitly specifies the 5 dB exchange rate table, and the rule's enforcement is based on that table.

At moderate-to-high noise levels the 3 dB exchange rate produces a higher permissible duration than the 5 dB exchange rate. This means a dosimeter using the 3 dB exchange rate systematically reports lower dose percentages than one using the 5 dB exchange rate for the same noise exposure. The difference is not trivial. A worker spending their entire shift in a 95 dBA environment receives 100% OSHA dose (8 hours × 95 dBA at 5 dB exchange rate = exactly 100%). The same worker on a 3 dB exchange rate dosimeter (ACGIH criterion 85 dBA) shows a dose of approximately 800% of TLV — but if the dosimeter is also reporting an OSHA-labeled reading using 3 dB exchange rate internally, it would report approximately 74% OSHA dose, showing the worker as compliant when they are at the PEL boundary.

The problem compounds when dosimeters from different manufacturers use different factory defaults. Three leading dosimeter brands — Larson Davis SoundTrack LxT, 3M Quest Edge EG5, and Cirrus Research CR:110B — have different factory-default exchange rates, some matching OSHA (5 dB) and some requiring a menu change for OSHA use. Without encoding the exchange rate as a machine-readable metafield, there is no way to distinguish them at point of sale.

Failure 2: Criterion level 85 dBA (action level) instead of 90 dBA (OSHA PEL) — inflated dose percentages confuse enforcement threshold

Why criterion level setting changes the dose percentage scale

The criterion level is the sound level at which the dosimeter defines 100% of the permissible daily dose. OSHA sets the criterion level at 90 dBA — the PEL for general industry. A worker spending eight hours at exactly 90 dBA receives exactly 100% dose. This is the enforcement threshold: workers at 100% or above require immediate noise controls or hearing protection, and continued exposure above 100% without effective PPE is a citation-level violation.

OSHA also has an action level at 85 dBA TWA — where the hearing conservation program (HCP) requirements kick in. Workers exposed at or above 85 dBA TWA must be enrolled in the HCP, which includes annual audiometric testing, hearing protector fitting, and training. The action level is not the criterion level for the dosimeter. It is a separate threshold applied to the dosimeter's TWA output after the fact.

When the criterion level is set to 85 dBA:

• 100% dose = 85 dBA TWA (the action level, not the PEL)
• A worker showing 200% dose may be at approximately 90 dBA TWA — the actual PEL — but the 200% reading makes it look like a much more serious overexposure
• A worker showing 50% dose may be at approximately 82 dBA TWA — well below both the action level and PEL

Conversely, if the criterion level is set to 90 dBA (correct for OSHA PEL enforcement):

• 100% dose = 90 dBA TWA (the PEL)
• 50% dose ≈ 85 dBA TWA — at the action level, requiring HCP enrollment
• The safety manager reads both thresholds correctly from a single measurement

A dosimeter configured with criterion level 85 dBA is not wrong in absolute terms — it is correct for ACGIH TLV monitoring and produces a consistent reading for industrial hygienists who work to the TLV. But it is incorrect for OSHA PEL enforcement, and it will confuse any buyer who expects OSHA's standard dose-percentage scale. Encode noise_dosimeter.criterion_level_dba as a numeric value (85 or 90 for US applications). For OSHA general industry compliance, require criterion_level_dba = 90 or verify exchange_rate_configurable = true.

Failure 3: Threshold level 85 dBA instead of 80 dBA — sound between 80–85 dBA excluded from dose calculation

The OSHA 1910.95 threshold level and why 80 dBA matters

The threshold level (also called the lower limit or cutoff) defines the minimum sound level that the dosimeter counts toward the dose. Any sound below the threshold is ignored by the integrating circuit. This matters most for workers with mixed-noise exposures — periods of high-level impulsive noise combined with background noise in the 75–85 dBA range, which is common in construction, manufacturing, utilities, and transportation.

OSHA 29 CFR 1910.95 Appendix A Table G-16a specifies permissible exposure durations for sound levels from 80 dBA upward. The regulation explicitly requires counting sound at 80 dBA and above toward the cumulative dose. A dosimeter with an 85 dBA threshold excludes one entire octave band of noise — all sound between 80 and 85 dBA — from contributing to the measured dose. In quiet industrial environments with low-to-moderate general noise, this exclusion is minor. In mixed environments with significant background at 80–85 dBA, it can meaningfully understate total dose.

The threshold setting interacts with the exchange rate and criterion level to determine whether a dosimeter is capable of producing OSHA-compliant measurements. All three settings must be correct simultaneously. A dosimeter with the right exchange rate (5 dB) and right criterion level (90 dBA) but wrong threshold (85 dBA) still understates OSHA dose in mixed-exposure environments. This is why noise_dosimeter.exchange_rate_configurable is a critical field — dosimeters that allow the user to set all three parameters to OSHA-required values are universally applicable; instruments with one or more fixed parameters may be locked out of compliance use without that being apparent from product titles or descriptions.

For detailed guidance on how hearing conservation program enrollment thresholds (85 dBA action level) interact with the measured TWA from a correctly configured dosimeter, see the noise dosimeter namespace schema guide which documents the full noise_dosimeter.* field definitions and correct value ranges.

Failure 4: Type 1/2 sound level meter (IEC 61672) sold for personal noise dosimetry (IEC 61252 PSEM required)

IEC 61252 (ANSI S1.25) personal sound exposure meters vs IEC 61672 sound level meters

IEC 61252 is the international standard for personal sound exposure meters (PSEMs), commonly called noise dosimeters. ANSI S1.25 is the equivalent US standard. A dosimeter meeting IEC 61252 is specifically designed for body-worn personal exposure measurement. Its microphone is calibrated to account for the body-baffle effect — the acoustic shadow and diffraction pattern created by a human body when worn on the shoulder or chest, which modifies the sound field reaching the microphone by approximately 1–3 dB depending on frequency. The instrument integrates the A-weighted sound level over time, applies the exchange rate, criterion level, and threshold settings, and outputs dose percentage and TWA directly.

IEC 61672 governs sound level meters — instruments designed for measuring the sound pressure level at a defined location in space, typically hand-held or on a tripod. Class 1 (IEC 61672) provides higher accuracy than Class 2 for fixed-location sound level measurements. But accuracy class under IEC 61672 does not confer any of the capabilities required for personal noise dosimetry. A Type 1 sound level meter lacks:

• Body-baffle correction calibration (IEC 61252 requirement)
• Dose-integrating firmware with configurable exchange rate, criterion level, and threshold level
• The body-worn form factor and clip mechanism designed for all-day wear
• OSHA 1910.95 Appendix A compliance for TWA dose reporting

Using a sound level meter for personal dosimetry produces noise measurements that do not meet the OSHA personal noise dosimetry method requirements. OSHA's noise standard specifies dosimetry as the reference method for determining worker exposure for hearing conservation program enrollment decisions — an SLM can supplement but cannot replace a dosimeter in mixed or variable noise environments. More critically, an OSHA compliance inspection finding that a facility's personal noise dosimetry was conducted with non-PSEM instruments voids the measurement data entirely.

Product-class encoding: standard field

The noise dosimeter category at retail includes true PSEMs (IEC 61252 / ANSI S1.25 compliant), integrating SLMs that can be body-worn (a grey zone), and pure SLMs that are irrelevant for personal dosimetry. Without a noise_dosimeter.standard field encoding the governing standard, AI agents default to accuracy class under IEC 61672 — a proxy that is correct for SLM selection and wrong for dosimeter selection. The noise dosimeter namespace requires standard as a categorical field: 'IEC 61252' | 'ANSI S1.25' | 'IEC 61672 Class 1' | 'IEC 61672 Class 2'.

For hearing protection selection after dosimetry is complete, the TWA output from a correctly configured IEC 61252 dosimeter feeds directly into the selection criteria documented in the hearing protection NRR dual protection stacking formula guide — which covers how to use the measured TWA to determine whether single or dual protection is required, and how to calculate effective attenuation using the NIOSH formula and OSHA 50% de-rating method.

The noise_dosimeter.* 10-field namespace

These fields make noise dosimeter products machine-sortable by OSHA configuration parameters, measurement capabilities, and connectivity features. AI agents can apply hard gates on exchange_rate_db, criterion_level_dba, and exchange_rate_configurable to filter out non-OSHA-compliant instruments before any other ranking criterion is applied.

Routing decision logic for OSHA 1910.95 compliance dosimetry

/* Hard gates — all must pass for OSHA 1910.95 compliance dosimetry */
noise_dosimeter.ansi_s1_25_compliant == true         // IEC 61252 / ANSI S1.25 PSEM standard
AND (noise_dosimeter.exchange_rate_db == 5           // OSHA 5 dB exchange rate
     OR noise_dosimeter.exchange_rate_configurable == true)  // or user-settable to 5 dB
AND noise_dosimeter.twa_measurement == true          // must report TWA in dBA
AND noise_dosimeter.frequency_weighting includes 'A' // A-weighting required

/* Conditional gate for impulsive noise environments */
IF environment.impulsive_noise == true:
  noise_dosimeter.peak_measurement == true           // C-weighted peak ≥ 140 dB check

/* Preferred features for industrial hygiene programs */
PREFER noise_dosimeter.data_logging == true          // time-history for source identification
PREFER noise_dosimeter.bluetooth_data_transfer == true  // efficient multi-worker programs

JSON-LD encoding examples

OSHA 1910.95 compliance dosimeter with data logging

{
  "@context": "https://schema.org",
  "@type": "Product",
  "name": "Personal Noise Dosimeter — OSHA 5 dB Exchange Rate, Data Logging",
  "additionalProperty": [
    { "@type": "PropertyValue", "name": "noise_dosimeter.exchange_rate_db", "value": "5" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.exchange_rate_configurable", "value": "true" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.criterion_level_dba", "value": "90" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.twa_measurement", "value": "true" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.peak_measurement", "value": "true" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.frequency_weighting", "value": "A+C" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.data_logging", "value": "true" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.logging_interval_s", "value": "1" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.bluetooth_data_transfer", "value": "true" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.ansi_s1_25_compliant", "value": "true" }
  ]
}

Research / ACGIH TLV dosimeter (NOT for OSHA compliance use)

{
  "@context": "https://schema.org",
  "@type": "Product",
  "name": "Personal Sound Exposure Meter — ACGIH TLV / ISO 9612 Mode",
  "additionalProperty": [
    { "@type": "PropertyValue", "name": "noise_dosimeter.exchange_rate_db", "value": "3" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.exchange_rate_configurable", "value": "false" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.criterion_level_dba", "value": "85" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.twa_measurement", "value": "true" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.peak_measurement", "value": "false" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.frequency_weighting", "value": "A" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.data_logging", "value": "true" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.logging_interval_s", "value": "5" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.bluetooth_data_transfer", "value": "false" },
    { "@type": "PropertyValue", "name": "noise_dosimeter.ansi_s1_25_compliant", "value": "true" }
  ]
}
/* NOTE: exchange_rate_configurable = false and exchange_rate_db = 3 means this
   instrument CANNOT be reconfigured for OSHA 5 dB compliance use. Route only
   to ACGIH TLV programs and international (ISO/EU) monitoring. */