Environmental noise is a major issue in most countries, especially in areas of high population, and the sources of noise and their adverse effects on our well-being are varied. In terms of assessing the impact of these issues, we need to be able to make suitable noise measurements, or in some cases monitor the noise levels for longer periods.
Industrial noise, for example, is a much more exact science, as you are interested in assessing specific noise levels and relating these to legislative or action levels.
Environmental noise is very different because the level of annoyance or nuisance can be very subjective and will elicit diverse reactions from different people.
Examples of typical noise sources:
Environmental noise can also have different characteristics:
1. Basic noise level checks or ‘spot checks’
Often you need to take quick decisions and understand if there are likely to be any noise issues. By using a simple sound level meter such as the Model 14 you have a cost effective, compact and ‘easy to use’ instrument that can be easily transported, allowing you to make a quick judgement regarding noise levels. This is particularly useful where a more expensive instrument would be cumbersome and more prone to the risk of damage or misuse.
The Model 14 is supplied with a wind-shield as standard to protect the microphone capsule and has two selectable ranges to allow you to quickly gauge both environmental and industrial level noises. The instrument is compliant with IEC 61672 and can be supplied with an acoustic calibrator if you wish to verify your measurements – as really should be done.
2. Single but more detailed measurements
Environmental requirements and legislation vary based on your country, locality and specific circumstances.
Often a hand held integrating sound level meter such as the Model 30 would be mounted on a tripod at a boundary position and, for example, a 15 minute measurement made. Often it is necessary to make a series of similar ‘fixed duration’ measurements and store these into the instruments memory (for subsequent analysis) for which the Model 30 or Model 33 are ideal. The usual stored information may consist of the ‘A’ Weighted Leq, LN values, SPL values and perhaps 1:3 Octave Band information for tonal analysis.
Typical view of a 1:3 Octave Band Analysis using Acoustic Toolbox software.
3. Longer term monitoring
Tonal_AnalysisSometimes we need to monitor noise levels on an ongoing level and make longer measurements sub-divided by shorter measurement durations such as 5 minutes, 15 minutes or 1 hour. This allows us to look at, for example, a 24 hour period and find the average, background or maximum noise levels for every 15 minute period throughout the day. This gives us a much clearer picture of noise patterns and how they can be controlled to minimise their impact on the wider community. Often, lower noise limits will be set during the late evening and night due to the extra impact of any noise.
There are many engineering solutions available to reduce noise levels and by performing a 1:3 Octave Band Analysis before and after this work you can determine and report the effectiveness of such improvements.