Today, we’re discussing noise surveys. Whether in a bustling factory, a noisy office, or any place where sound levels can get out of hand, understanding how to measure and manage noise is crucial.
In this post, we’ll discuss the process of conducting an effective noise survey. We’ll explore why these surveys are so important, the tools you’ll need, and the step-by-step process to accurately assess noise levels in your environment. By the end, you’ll have the know-how to create a quieter, safer workplace for yourself and your team.
What You’ll Learn
- Importance of Noise Surveys: Understand why conducting noise surveys is critical for workplace safety and hearing protection.
- Tools and Techniques: Learn the essential tools and techniques to measure and assess noise levels accurately.
- Steps for Conducting a Noise Survey: Discover a step-by-step guide to performing a comprehensive noise survey, from preparation to evaluation.
Introduction
A noise survey may be required where noise has been identified as a risk to workers. The noise survey can also be conducted to assess the effectiveness of engineering controls in place or the type of hearing protection devices that are being utilized.
A detailed noise assessment may then be conducted using a Sound Level Meter (SLM) or actual exposure measured with a Personal Sound Exposure Meter (PSEM). This will allow the A-weighted, equivalent sound pressure level and peak level to be determined.
Preliminary Noise Assessment
A preliminary or initial assessment should be conducted where noise has been identified as a risk at the workplace and a noise survey has not been previously conducted. In addition, if previous assessments have been performed but are more than five years old, an initial assessment should be conducted to obtain an overview of the state of conditions in the workplace.
Detailed Noise Assessment
A detailed noise assessment may be required if there is doubt as to whether the noise sources are placing workers at risk, if the noise sources are complex or if the noise levels are excessive. The detailed assessment involves measuring the 8-hour A-weighted, equivalent sound pressure level, and the peak level. The levels should be taken at work areas or on workers who may be at risk from noise exposure.
Follow-Up Noise Assessment
The follow-up noise assessment aims to check controls and the current status of noise exposure, although a noise assessment may have been previously conducted. An assessment should be carried out at least every five years or where any of the following have occurred:
- A change to the process that may have affected noise exposure
- Additional equipment or plant have been added to the workplace
- Changes in work procedures that could have affected noise exposure.
Conducting the Noise Survey
The first step in conducting the noise assessment is to calibrate the Sound Level Meter (SLM) or Personal Sound Exposure Meter (PSEM). While there are many sound measurement applications (apps) available for iOS and Android platforms, not all met the accuracy requirements of Type 1 and Type 2 sound level meters (Kardous & Shaw, 2016; Zamora et al., 2017).
For this reason, NIOSH developed a Sound Level Meter App which meets Type 2 requirements of IEC 61672:3 when used with an external microphone (CDC, 2019). Other researchers found the NIOSH app to have good accuracy (less than 2.0 dBA difference between the app and PSEM), and especially when measuring noise above 75 dBA (Jacobs et al., 2020).
The sound pressure levels are taken either on a worker or at a particular location where the worker spends their normal workday. The occupational noise exposure includes both immissions from equipment and plant, as well as other noise from radios, sirens, or warning signals. Where a person occupies one work area, the sound pressure levels are taken at this location. However, most workers are exposed to noise in different work locations. Therefore, the sound pressure levels are measured in each of these locations, and the duration of exposure determined to calculate the partial noise dose and daily noise dose.
The microphone should be located about 10 cm but not more than 20 cm from the entrance of the external canal of the ear receiving the higher noise level, at a level that is horizontal to the ear. If this is not practical, a person can be removed from the area and a measurement is taken at the location where they would have been. If a PSEM is being worn, the preferred location of the microphone is the top of the shoulder, close to the ear.
The equivalent, continuous sound pressure level should be measured over a representative period of the operation, process, or work pattern of exposure. The duration of monitoring should include any process or procedures that could significantly vary the noise level (e.g. machines switching on).
No matter the duration of the measurement, it should be either the entire length of the task or a portion of the task where the equivalent sound pressure level can be assessed.
Data to Collect When Conducting the Noise Survey
When conducting the noise assessment, adequate information should be kept both as evidence if required due to litigation and as a benchmark for the future. Some information that should be kept includes:
- Details of the workplace (location and nature of work)
- Description of the work environment, including nature of work process and tasks; acoustic characteristics of the workplace (e.g. reflective walls and panels, absorbing materials, open areas); working hours for a normal day; the number of workers in various areas; alterations to the workplace compared with a previous assessment; job description or designation where the measurements are taken; and details of current controls, including hearing protection devices
- Noise assessment details such as the brand and type of sound measuring instrument; operating conditions; during the measurement period; locations of measurement; time-in-motion study of various tasks during a typical day; and individual time periods of exposure if the partial noise dose is to be determined
- Results of the noise assessment
- Name and signature of the person conducting the survey
- Date of the assessment.
Summary
A noise assessment may then be conducted using a Sound Level Meter (SLM) or actual exposure measured with a Personal Sound Exposure Meter (PSEM). This will allow the A-weighted, equivalent sound pressure level and peak level to be determined.
Helpful Resources
- Occupational Noise and Workplace Acoustics, by Dariusz Pleban
- Occupational Noise Management Blog Post, by Megan Tranter
Bibliography
CDC. (2019, January 3). NIOSH Sound Level Meter App. The National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/topics/noise/app.html
Jacobs, N., Roberts, B., Reamer, H., Mathis, C., Gaffney, S., & Neitzel, R. (2020). Noise exposures in different community settings measured by traditional dosimeter and smartphone app. Applied Acoustics, 167(October). https://www.sciencedirect.com/science/article/abs/pii/S0003682X20305120?via%3Dihub
Kardous, C., & Shaw, P. (2016). Evaluation of smartphone sound measurement applications (apps) using external microphones—A follow-up study. The Journal of the Acoustical Society of America, 140(4). https://asa.scitation.org/doi/full/10.1121/1.4964639
Zamora, W., Calafate, C., Cano, J.-C., & Manzoni, P. (2017). Accurate Ambient Noise Assessment Using Smartphones. Sensors, 17(4). https://www.mdpi.com/1424-8220/17/4/917
