Noise Measurement-January 2020

Monthly Round Up of Important Ideas and Standards in
Industrial Hygiene and Safety

January 2020

IN THIS ISSUE: Noise Measurement

Workplace hearing conservation begins by identifying locations and tasks where employees may  be overexposed to noise and equipment that may be contributing to noise at the facility. Measuring noise levels and worker exposures are an important part of that effort.

Employee exposures to noise are determined by taking measurements with a sound level meter (SLM). It is an instrument that is used to determine instantaneous noise levels. A SLM consists of a microphone, electronic circuits and a readout display. The readout shows the sound level in decibels. If noise levels exceed 85 decibels on the A-scale (dBA) in a work area, further testing and evaluation may be required. A SLM may also help identify noisy machinery. Some devices can be equipped with an octave band analyzer, which breaks down noise into various frequencies and octaves. This device can pinpoint the specific part within a machine that is the source of the noise. These findings may indicate the need for better maintenance, noise cancelling devices, or replacement with less noisy equipment.

If noise levels exceed 85 dBA in a worker’s area, it is important to determine his/her average exposure during the shift since noise usually varies in duration and intensity, and may vary by location. A noise dosimeter, a small, lightweight device that includes a  microphone that fastens to the person’s collar, close to the ear, is used.  The dosimeter stores the noise level information and carries out an averaging process.

The dosimeter can be set to measure noise based on regional regulations. In the US, OSHA uses the A-scale, which is intended to indicate perceived loudness and provide a rating of industrial noise that indicates the impact that particular noise has on human hearing. It measures speech frequencies between 500 and 4000 Hertz with the highest weighting at 1000 to 4000 Hertz. OSHA uses two measurements  for noise: The Action Level of 85 dBA or a 50 percent dose is used to determine whether a hearing conservation program is needed and the Permissible Exposure Limit (PEL) of 90 dBA or a 100% dose determines whether engineering controls are necessary and whether parts of hearing standard are mandatory. Each uses a different a method for measuring noise. Most dosimeters are preset to measure both of these criteria.

In the United States, hearing loss is the third most common chronic physical condition after high blood pressure and arthritis and is among the most common work-related illness. It is important that employers determine if their workers are at risk for hearing loss. Taking noise measurements and comparing them to occupational exposure limits is an important step in making that determination

For more information on this topic and to discuss your company’s safety and industrial hygiene needs call OccuSafe at (214) 662-6005 or visit us at

OccuSafe Industrial Hygiene & Safety, Inc. provides skills and expertise to recognize, evaluate and control hazards and injuries in the areas of industrial hygiene, occupational safety and health. OccuSafe services companies of all sizes in a range of industries.

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