You are planning to carry out a noise measurement and are looking for a measuring instrument that suits your specific application. When do you use which instrument, and which standard do you have to comply with? The equipment comes in all shapes and sizes, so it is easy to lose track of all the options. In this article we distinguish between the different measuring instruments and describe what the standard expects of you.
Occupational noise
You are planning to measure your employees' exposure in accordance with ISO:9612 — how do you go about it? At BaSystemen we mainly come across two approaches: dosimetry and noise maps. With dosimetry, measurements are taken using a dBadge 2 noise dosimeter. This is a small sound level meter with a class 2 microphone that can be attached to the shoulder (we explain the difference with a class 1 microphone later in this article). The microphone sits as close to the ear as possible in order to determine the exposure as accurately as possible. The dosimeter is worn throughout an 8-hour working day so that the total exposure during the work can be determined. Highly suitable for measuring work that is similar every day.
For work without a fixed pattern it is harder to take a measurement that is representative of an ‘average working day’. In these cases we often see companies producing noise maps. Measurements are then taken with a class 2 sound level meter at various points on site to build up a picture of the noise level in a given area. This determines in which areas hearing protection has to be worn.
A special application is gunfire noise. This may involve shooting ranges with portable projectile weapons or, for example, artillery. Here the measuring range of the sound level meter is often the bottleneck. Usually the range stops at 143.5 dB. A solution for this would be a high-range microphone with a range up to 165 dB.
Noise nuisance (environmental measurements)
As mentioned above, occupational noise measurements are aimed at protecting staff against harmful noise. Environmental measurements, by contrast, are aimed at measuring nuisance noise. This does not necessarily have to be directly harmful to the people exposed to it, but it can certainly be experienced as unpleasant. Think of motorways, air traffic, festivals or, for example, a factory in a residential area.
In a large proportion of these applications, a measuring instrument with a class 1 microphone is required. For example, ISO:20906:2009 ‘Unattended monitoring of aircraft sound in the vicinity of airports’ states that measurements must be taken with an instrument that meets the electroacoustic specifications of IEC 61672-1 for a class 1 sound level meter.
Suitable for this is the Guardian 2 environmental monitor, which sends its data straight to the internet and can be checked anywhere in the world. A more portable option is the class 1 sound level meter.
Ultrasound
Something of an odd one out is ultrasound. This concerns frequencies that we humans cannot hear. For example a leaking pipeline from which gas escapes under high pressure. This can be detected with an ultrasonic leak detector. Here the focus is therefore not on hearing damage or nuisance, but on the escape of raw materials or waste substances.
Still in doubt about the right instrument for your application, or do you have other questions related to this article? Call our specialists:
