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At OMY, we suggest that companies create a sound map (sometimes referred to as “noise diagrams” or “noise” maps) of their facilities. If you’re not familiar with sound maps, they’re exactly what they sound like: hand-drawn, birds-eye-view maps that indicate the different sound levels for the various departments.

With smartphones, it is very easy to check the noise levels using decibel meters – many of which are inexpensive or even free. It only takes a few second to perform a preliminary check using basic sound level readings. The OSHA inspector will use more sophisticated equipment over longer periods of time, but having this basic information on-hand from the start will make the process go as smoothly as possible.

When it comes to sound maps, clarity is more important than artistry, but in order to get the most out of your sound map, it should include as much relevant information as possible.

Here are a few reasons why you should create a sound map as well as a guide to collecting information and presenting it in a way that is beneficial to employees, employers and inspectors.

Benefits of a Sound Map for Employees and Employers

The primary benefit of preemptively creating a sound map is employee safety. Creating a sound map will identify potential safety risks throughout the facility. Once identified, the potential problems can be remedied before injuries occur. Proper hearing protection can be distributed and employee exposure can be minimized. Accordingly, taking these steps before the inspector arrives can lessen the risk of potential OSHA violations.

Benefits of a Sound Map to OSHA Inspectors

It is likely that you will be visited by an OSHA inspector who is unfamiliar with your facility. If they’ve been to your site before, it has likely been more than a year since their last visit and they’ve visited a lot of facilities in the meantime. Handing them a sound map upon their arrival will help them get started right away and make effective use of their time. They will want to monitor for an entire shift, so it helps to get as much squared away as possible before they arrive. Additionally, they will have a lot of specific questions about your facility such as dimensions and construction materials, and it helps to have this information handy.

Creating the Sound Map

The OSHA inspector will use a variety of pieces of equipment to assess the workspace. Particularly, they will use a Sound Level Meter, an Octave Band Analyzer and a Noise Dosimeter. It might be a good idea for your company to invest in these items and learn how to use them. However, to create a rudimentary sound map all you need is:

  • A tape measure
  • A pen and paper (preferably graph paper)
  • A decibel-measuring app on your smartphone

It is ideal to use plant schematics and blueprints to sketch the workspace, but the tape measure, pen and paper can also be effective.

Step 1: Begin by taking a reading adjacent to the equipment. Mark the dB reading on the paper.

Step 2: Move backwards from the equipment while continuing to take readings.

Step 3: When you find a distance where the noise level drops to a safe level, mark it on the paper.

Step 4: Draw an arc around the equipment that crosses through the point where the noise level drops to a safe level to establish a “hazard radius.”

Step 5: Repeat this process for other equipment in the facility. Pay particular attention to the areas where the radiuses overlap. In these areas, the inspector will use a specialized piece of equipment called an Octave Band Analyzer to further examine the risks associated with specific pieces of equipment in designated areas on the floor.

Keep this map in a safe place to assist the OSHA inspector when they arrive, but also use this experience as an opportunity to go over hearing protection and other safety concerns with employees.

Tips for Including Dosimeter Readings in Your Sound Map

OSHA will also be concerned with the Time-Weighted Average (TWA) of the noise levels that employees are exposed to throughout the duration of a typical shift. To gain a more sophisticated idea of the noise levels that your employees are exposed to, a dosimeter can be used to create or supplement your company’s sound map.

Dosimeters are more specialized and less pervasive than smartphones, but on account of OSHA’s emphasis on TWA, we highly recommend that companies incorporate dosimeter readings in their sound maps.

Dosimeters are worn by the employees for the duration of a shift. Depending on the work environment, dosimeters are commonly clipped onto the outer layer of an employee’s uniform with care being taken to prevent it from interfering with the employee’s tasks.

It can also be worth explaining to employees that while they are technically wearing a very sensitive microphone, dosimeters only measure the loudness of sounds. They do not record the sounds themselves. Dosimeter readings are purely for safety purposes.

While all dosimeters can be used to identify an employee’s TWA, some include additional features that can help to further analyze and breakdown the findings such as:

  • The ability to identify the single loudest noise that employees are exposed to throughout the shift
  • Graphing functions that visually represent the sound exposure and indicate the noise “trends” of the shift

Here are some other things to keep in mind when using a dosimeter in your facility:

  • The dosimeter must be exposed to open air
  • Wind noise is unacceptable and can be reduced by using a windscreen
  • Care should be taken to run wires through layers of clothing to ensure that it doesn’t interfere with the employee’s work
  • Make sure that the batteries are fresh
  • Make sure that the dosimeter is properly calibrated

More information about how OSHA uses dosimeters can be found here.

You don’t have to be an OSHA inspector to identify and fix potential safety hazards. In fact, it’s easier and safer all around to take the initiative yourself before any problems arise. Taking the initiative and creating the sound map now will help eliminate potential “surprises” on inspection day.

If you have any questions about Audiometric Testing or creating a sound map in your facility, feel free to contact us!

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