# Video: Noise measurements

This is a video clip of 1 min 36 seconds showing how to measure noise levels at a work place. You may use this video if you teach in occupational health about  how to measure noise.

To know whether or not the noise is a risk factor for health at the workplace the employer need to know the quantity of the noise exposure. For noise there is a “rule of thumb” that if you have to shout to make yourself heard then the noise is loud enough to cause negative health effects. Often you can get an opinion about the amount of exposure by visiting the workplace and listening to the experiences the workers have. Sophisticated measurements are not always needed. If it is difficult to communicate at the workplace, you can assume that the noise level is above 85 dB(A). To quantify the exposure more accurately, there are two different methods for noise measurements;

Area measurements measures the sound in certain areas using a sound level meter. The level of and the different frequencies the noise is composed of is measured in different locations. This is very helpful to map exposure and design sound contour maps, which are often used both at workplaces and in public areas. Such maps are used, for instance, to mark areas were special hearing protection is needed, or used for planning different protective measures, such as noise source isolation and personal measurements.

The other method to perform noise measurements are done through small instruments, called dose meters, which are used to monitor the noise levels the worker is exposed to during the working day. The noise dose meters can be used to monitor workers who change their work place or work task during the day. The instrument is attached and placed on the workers shoulder at the beginning of the workday or before performing specific tasks as shown in the video and when the worker notes his activities during the day it may be used to detect specific exposure situations.

In addition, it is possible to evaluate noise levels by theoretical calculations. Specific methods concerning how to perform noise measurements, and how to calculate noise exposure, are thoroughly described in certain ISO standards.