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2.4.4 Noise
measurements
2.4.4.2 The process of measuring
As climatic conditions can influence noise measurements, these influences have to be taken into account during the planning of measurements. In order to prevent background noise from wind, the microphone must be equipped with a windbreak out of porous foam
(fig. 2/11d). What also has to be considered is the fact that the results can differ substantially depending on the wind direction and wind force. This is also true in times of temperature inversion, when sound is reflected and can be perceived over long distances. If the ground is frozen or covered with snow, the absorption properties of the soil may vary significantly, just like the rolling noise of cars can be changed by rain.
The priority as for noise measurements lies in the compliance with the relevant regulations. The following aspects play a particular role:
| Parameters: |
Are determined by the frequency and time weighting at the measurement device (e.g. A and f).
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| Measurement
device: |
Determines the exactness of the measurement (requirement of the norm).
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| Measurement
location: |
Determination of the microphone localization depending on the task and environmental conditions.
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| Measurement
period: |
Is determined by the task and noise situation. The measurement period must be long enough to deliver representative results. What has to be prevented is the impact of extraneous sounds on the measurement results.
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| Noise
status: |
The noise source must possess the adequate operating status.
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| Analysis
method: |
Delivers the final assessment on the basis of single measurements, e.g. after the consideration of additions (measuring time, noises with discrete components etc.).
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