Personal Noise Dosimeter

What is the Personal Noise Dosimeter?

A compact body-worn instrument that measures a worker's noise dose over a shift using a microphone at the shoulder, reporting Leq, TWA and percent dose. It is the right choice for occupational hearing conservation programs where exposure varies with movement between work areas.

Overview

The dosimeter is clipped to a belt with a small microphone mounted on the collar or shoulder near the ear. It integrates sound levels over a workshift, typically eight hours, and calculates the dose as a percentage of an allowable limit based on a chosen criterion level such as 85 dB(A) with a 3 dB exchange rate, or OSHA's 90 dB with 5 dB. Outputs include TWA, Leq, Lmax, peak levels, and time above a threshold. Modern units log a time history each second, allowing correlation with tasks, and dock to software that prints reports. Lightweight designs weigh under 100 g, and lithium batteries last over 30 hours. Units conform to IEC 61252 and are calibrated before and after each shift with a pistonphone or calibrator.

How does it work?

A noise instrument converts sound pressure into an electrical signal with a calibrated condenser or MEMS microphone. The signal passes through frequency weighting filters, most commonly A-weighting that approximates human hearing, and C-weighting for peak and low-frequency content. A detector with exponential time weighting, Fast at 125 ms or Slow at 1 s, or an integrating stage produces the level in decibels relative to 20 µPa. Equivalent continuous level Leq, percentile levels such as L10 and L90, maximum and peak levels and sound exposure level are computed digitally. Class 1 instruments have tighter tolerances than Class 2 under IEC 61672-1. Octave or third-octave filter banks and FFT analysis add frequency information, and acoustic calibrators at 94 dB and 1 kHz check sensitivity. Permanent stations add weather protection and telemetry.

What are the key features?

• Body-worn design under 100 g records noise exposure for a full eight-hour shift.
• Selectable criterion levels and exchange rates meet ISO, OSHA and GBZ 2.2 requirements.
• One-second time-history logging links exposure peaks to specific tasks.
• Tamper-resistant lock mode prevents workers from altering settings during the shift.
• Docking cradle downloads data and prints dose reports automatically.
• Peak detector records C-weighted impulse levels up to 143 dB(C).

What are the technical specifications?

A typical personal noise dosimeter configuration offers measurement range of 60–140 dB(A), peak range of Up to 143 dB(C), criterion level of 80, 84, 85, 90 dB selectable, exchange rate of 3, 4 or 5 dB selectable, frequency weighting of A, C and logging interval of 1 s time history. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Personal Noise Dosimeter is used in hearing conservation programs, factory and plant exposure surveys, mining and construction noise dose and airport ground crew monitoring. Across the wider Noise Monitoring class, laboratories also deploy it for community and environmental noise assessment, construction site noise compliance and occupational noise exposure surveys.

Which standards and certifications apply?

Relevant standards and methods include IEC 61672-1, IEC 61672-3, IEC 60942 (sound calibrators), ISO 1996-1, ISO 9612, IEC 61252 (personal exposure meters), GB 3096 and GB/T 3785.1. Certification candidates for this model are CE, China pattern approval and ATEX or IECEx for Ex version; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Calibrate with an acoustic calibrator before and after each measurement session and record any drift, which should be under 0.5 dB. Use a windscreen outdoors, keep the microphone 1.2 to 1.5 m above ground and at least 3.5 m from reflecting surfaces for free-field environmental measurements, and avoid rain or condensation on the capsule. Record weather conditions because wind above 5 m/s invalidates many measurements. Instruments need periodic verification in an accredited laboratory, typically every one to two years, following IEC 61672-3. Store in dry conditions, replace batteries before long campaigns, and preserve raw time history when regulators may audit the data. Permanent stations require protection from birds, vandalism and lightning.

How do I select the right Personal Noise Dosimeter?

Select a dosimeter when workers move between areas or noise varies with time, so fixed measurements cannot represent exposure. For mapping noise sources in a room, use a sound level meter instead. In an RFQ, specify criterion and exchange rate, lock mode, intrinsic safety, software and calibration kit.

How does it compare with other Noise Monitoring variants?

Choose the class and type according to the regulation: Class 1 for environmental noise assessment and legal evidence, Class 2 for general surveys and workplace screening. Decide between handheld meters for spot checks, dosimeters for worker exposure and permanent stations for continuous site monitoring. Check the level range, such as 20 to 140 dB, and whether the dynamic range covers both background and peak events. For industrial and product noise, frequency analysis in octave or third-octave bands is needed. Consider data storage, time-history logging with audio recording for source identification, IP rating, temperature range and battery life. For permanent installations, evaluate microphone protection, communication and power. Confirm that the supplier offers IEC 61672-3 periodic verification and traceable calibration.