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Noise Monitoring: Listen up

Noise Monitoring: Listen up...

Construction - Noise risks

Every year, according to OSHA, approximately 22 million workers in the United States are exposed to potentially damaging levels of noise at work, and compensation for noise-induced hearing loss costs the economy an estimated $242 million. Noise in the workplace can be unavoidable, particularly when workers operate high-powered tools and machinery. Some of the loudest tools in the workplace include belt sanders (93 dB), bulldozers (105 dB), chain saws (110 dB), and pneumatic drills (119 dB).

Employers should be monitoring noise levels to ensure they don’t exceed regulatory limits and affect workers’ health. Monitoring provides concrete exposure data that can highlight key areas for change. An effective noise measurement program can lead to clear improvements in workplace noise levels and, most importantly, reduce employee exposure.

OSHA requires employers to implement a hearing conservation program for workers who could be exposed to an average level of 85 decibels over an eight-hour work shift. The OSHA standard also shows impulsive or impact noise should not exceed 140 dB and continuous noise should not exceed 115 dB.  

Noise monitoring delivers accurate insights into workers’ exposure, showing specific areas of concern. With many devices on the market, it can be difficult to identify what type of product is most suitable for your working environment. Is it better to use a noise dosimeter or a sound-level meter, and what are the differences between the two?

Sound-level Meters

A sound-level meter is a handheld device that enables measurements to be taken at the ear (within 10–15 cm) with the instrument pointed at the noise source. This process must be repeated for both ears, for all duties employees perform. The settings on these meters can be adjusted, according to the type of noise being assessed. Monitors should be compliant with the ANSI S1.4 – 1983 (R2006) standard. Data collected through sound-level meters can also help with developing noise controls.

When using a sound-level meter, measurements must be started at the beginning of a task. If workers are likely to be exposed to high levels of impulsive noise—for example, from heavy pressing operations or sheet metal working—peak noises must be measured for accurate results and compared to peak action levels.

Sound-level meters are the preferred supporting device for noise surveys because the operator is present to ensure the quality of the readings. For each job function, a representative measurement is made and the exposure time, ensuring that an eight-hour exposure can be calculated.


Dosimeters are small devices worn by workers for measuring personal exposure. Dosimeters can be used for an entire shift, and then data can be uploaded onto a computer. The data details the history of the noise exposure. If the employee wears a dosimeter and keeps a diary of times and jobs performed throughout the day, the employer will be able to instantly identify the operations with increased noise levels that require more effective noise controls.

It is best to use dosimeters for individuals with a complex work pattern and varying noise level exposure, or for tasks that are difficult to monitor with a sound level meter (for example, driving a fork lift). It is important to remember that noise dosimeter measurements are open to spurious results caused by employees tampering with measurements, especially when first used. High exposures should be investigated to see if they are a legitimate part of the worker’s exposure. Modern noise dosimeters can record the actual audio and allow the sound to be played back to determine what the exposure was from, such as a particular machine, or indeed that it was spurious.

In keeping with regulatory requirements, employers must purchase dosimeters that are compliant with the ANSI S1.25 – 1991 (R2007) standard.

Monitoring Solutions

Tim Turney, Technical Product Manager Casella

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This article was published in the AIHA online magazine


AIHA: Protect Yourself from Noise-induced Hearing Loss.
OSHA: Occupational Noise Exposure: Overview.
OSHA: Occupational Noise Exposure: Standards.