Noise Measurement – Using a Sound Level Meter vs. Dosimeter

Business regularly conducts noise assessment to determine noise level in the workplace that their workers’ exposure. It is a legal requirement that your take appropriate measure to ensure your employees is not exposed to noise level above the exposure standard.

The exposure standard is LAeq of 85 dB (A) or LCpeak of 140 dB (C). LAeq means the eight-hour equivalent continuous A-weighted sound pressure level that denotes the average noise exposure over a period of 8 hours. LCpeak means C-weighted peak sound pressure level that indicates the peak noise generated during work.

The most popular methods to measure the noise levels are either by using a sound level meter or dosimeter. The central question that many business owners & manager have is should they use a sound level meter or dosimeter to do the job. Before answering that question, we need to understand some basis

Dosimeters

A dosimeter is a special purpose sound level meter that is small enough that your worker can wear the shift. Dosimeter will measure the noise level exposure wherever your worker goes and does throughout the workday. Usually, dosimeters along with the microphone come with a small pin or clip so that you can clip to workers’ shirt. Most dosimeters operated on batteries that can be charged before deployment.

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Advantages of Dosimeter

The standard practice is dosimeter is clipped to the worker, whose noise exposure needs to be measured, during the start of the shift and after removed after the work shift. The output of dosimeter shows the time-weighted noise exposure for 8 hours. Data from the dosimeter is then downloaded unto a personal computer with the help of the software and details about the noise exposure throughout the day is determined.

  • Provides noise level measurement specific to specific worker
  • Help the business in managing OHS claims regarding noise
  • Results from the dosimeter can be reported as compliance with state OHS regulations
  • Easy to use and does not require a noise assessor to be present through the day
  • Since modern dosimeter are light and small, it can be clipped to the worker easily and will have minimal disruption during work
  • Used in restriction or controlled environment where noise assessor cannot use sound level meter
  • Can measure and provide results both LAeq & LCpeak

Disadvantages of Dosimeter

  • Easy to overestimate the noise level if the microphone of the dosimeter is inappropriately placed in a position that has the risk of other noise due to reflection, surface friction or impact.
  • Difficult to identify the accurate source of noise as the employee may work in any area throughout the day.
  • Influence or other sounds nearby such as forklift rumbling, public announcement system, working operator, conversation with others can affect the results
  • Sound exposure during break times will also be calculated
  • In some cases, workers can tamper the dosimeter, and the whole noise assessment is not controlled or monitored
  • Require specialist skills to set the dosimeter, download the information using specific software and prepare the report.
  • Sometimes purchasing or hiring a dosimeter can be expensive than a sound level meter.
  • Does not provide information or opportunities to identify how to reduce noise level as we cannot identify the primary source of noise form.

 

Sound level meters

A sound level meter is handheld noise measuring device with a microphone. It is also called a Sound Pressure Level (SPL) Meter as the diaphragm in the microphone responds to change in the air pressure created by sound waves. Hence a sound level meter can instantly measure current sound pressure level (SPL) in an environment.

A noise assessor can then use the sound level meter is two different ways to measure noise level.

  1. Static noise measurement – The sound level meter is mounted on a tripod (almost 1.2 meters from ground level) and takes measures the SPL of the environment over a period.
  2. Ear level noise measurement – The sound level meter is held around 0.1 to 0.2 meters from the worker’s ear canal entrance over a period and measures the SPL exposed. A noise assessor can the use the sound level meter is two different ways to measure noise level.

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The user/noise assessor can control the sound level meter and can use on different locations in the workplace. Most sound level meters have a display that quickly shows the dB level and also a software companion that can download the data unto a personal computer. You should remember that sound level meter only measures a sample of noise as ‘snapshot’, and the results should be converted to LAeq (A –weighted) average of 8 hours. Noise levels of individual pieces of equipment or operated can be determined, and a noise map can be developed for the workplace.

Advantages of Sound level meter

  • Provides detail information about the source of noise
  • Help the business in managing OHS claims regarding noise
  • Results from the dosimeter can be reported as compliance with state OHS regulations
  • Easy to use and does not disturb the worker
  • Recommended practice by the Victorian code of practice
  • Information collected using sound level meter can be used to draw a noise map of the site and also finds opportunities to reduce the noise level.
  • Can measure and provide results both LAeq & LCpeak
  • In most cases, it is cheaper to purchase or hire a sound level meter
  • Sound level meter can be used to measure a specific situation or activity or machine operation
  • If needed, noise level and immediately re-measured with ease.

Disadvantages of Sound level meter

  • Need a skilled resource to conduct a noise assessment using sound level meter
  • Sound level meter is difficult to use in controlled environments such as working at heights and confined space
  • The assessor needs to convert the data to 8 hours’ average.
  • There will be a minimum disruption to operational activity when sound level meters are used
  • Influence or other sounds nearby such as forklift rumbling, public announcement system, working operator, conversation with others can affect the results

Integrated noise assessment

You can also choose to use both sound level meter and dosimeter to determine the noise level in the workplace. It is recommended you engage an external service provider in measuring the noise level in your workplace because the regulation requires that noise measurement to be conducted by trained and competent individuals.

 

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