Workplace Noise Survey and Occupational Noise Exposure Assessment

Noise-induced hearing loss develops without pain, over years, and is irreversible by the time it is noticed. Assessment establishes who is exposed, to how much, and whether the controls in place are adequate, which is both a legal obligation in many workplaces and the only sound basis on which hearing protection can be selected. itmad provides workplace noise surveys and occupational noise exposure assessment, with area mapping, personal dosimetry, octave band analysis and hearing protection recommendations. itmad operates across the Middle East, Asia and Europe. Last reviewed: October 2026.

What itmad measures

A walkthrough area survey maps sound pressure levels across the premises, identifying which areas exceed action levels and where hearing protection zones should be designated, and establishes the scale of the problem before individual assessment. Personal dosimetry uses body-worn dosimeters to record a worker's actual exposure across a full shift, capturing the movement between quiet and noisy tasks that a fixed-point reading misses entirely.

Octave band analysis breaks the noise down by frequency and does not report a single figure, which is needed to select hearing protection correctly and to design engineering controls that address the frequencies actually present. Peak sound pressure measurement covers impulsive noise from impacts, pneumatic tools and pressure release, because peaks can cause immediate damage at levels that a time-averaged reading does not reveal.

Why octave band data matters

Hearing protectors do not attenuate equally across frequencies. A protector rated well overall may perform poorly at the frequencies that a process actually produces, so a single-number rating can suggest adequate protection where none exists, and octave band data allows selection by the HML or octave band method and not by SNR alone.

The opposite error is as common: over-protection. A worker in a moderately noisy area who is given high-attenuation protectors cannot hear warning signals, speech or approaching plant, and will remove them, which leaves them fully exposed. Correct selection targets the protected level into a defined range and does not reduce it as far as possible.

Assessment approach

The assessment starts with a review of the work pattern, identifying groups with similar exposure so that not everyone has to be measured. Instruments are calibrated before and after measurement, with drift recorded, and the measurement duration is representative of the full working period, including intermittent and occasional high-noise tasks. Daily personal exposure is calculated and normalised to an eight-hour equivalent, with weekly averaging where exposure varies substantially from day to day, and peak sound pressure is recorded separately from time-averaged levels. Existing controls and the use of hearing protection are observed and not assumed from policy.

Standards applied

Surveys follow ISO 9612 for the determination of occupational noise exposure, with instruments meeting IEC 61672 for sound level meters and IEC 61252 for personal dosimeters, and hearing protector selection follows ISO 4869. Assessment is made against the action and limit values in the client's governing regulation or HSE specification, and where a client applies a stricter internal limit, itmad assesses against that.

Where surveys are carried out

Manufacturing and process plant; construction sites and fabrication yards; power generation and utility facilities; oil and gas installations, onshore and offshore; workshops, compressor houses and pump rooms; and warehousing and materials handling operations. Surveys are also carried out after installation of new plant or a change in process, and in response to a worker complaint or an audiometry finding. Because dosimetry needs a full working shift, measurement is scheduled around the client's shift pattern and not office hours, including night shift work where that is when the noisy operations run.

What the client receives

A report that identifies the measurement locations and the personnel or groups assessed, with the measured levels, the daily personal exposure and the peak sound pressure against the applicable limits. It includes octave band data where measured and its implications for protector selection, and a noise map that identifies areas requiring hearing protection zones and signage. Specific hearing protection recommendations come with calculated protected levels, practical engineering and administrative control options are ranked by the control hierarchy, personnel who should be included in health surveillance are identified, and instrument calibration traceability is provided.

Related services

Noise assessment is often commissioned alongside environment and safety compliance auditing, where noise is one of several exposures under review, and alongside general safety training that covers the use and limits of hearing protection.

Frequently asked questions

What does a workplace noise assessment establish?

Who is exposed, to how much, and whether the controls in place are adequate. It is also the only sound basis for selecting hearing protection.

What does itmad measure?

Sound pressure levels across the premises in a walkthrough survey, personal exposure by body-worn dosimeters over a full shift, octave band data, and peak sound pressure. Peaks matter because they can cause immediate damage at levels that a time-averaged reading does not reveal.

Why does octave band data matter?

Hearing protectors do not attenuate equally across frequencies, so a protector rated well overall may perform poorly at the frequencies a process produces. Octave band data allows selection by the HML or octave band method and not by SNR alone.

Which standards apply?

ISO 9612 for the determination of occupational noise exposure, IEC 61672 for sound level meters, IEC 61252 for personal dosimeters and ISO 4869 for hearing protector selection. Assessment is against the limits in the governing regulation or client specification.

Why is over-protection a problem?

A worker in a moderately noisy area who is given high-attenuation protectors cannot hear warning signals, speech or approaching plant, and will remove them, which leaves them fully exposed. Correct selection targets the protected level into a defined range.

When is a noise survey commissioned?

On a regular programme, after new plant is installed or a process changes, and in response to a worker complaint or an audiometry finding. It is common in manufacturing, construction, power generation and oil and gas.