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Unattended environmental noise measurements are commonly undertaken to measure background noise, to check compliance to established noise limits, investigate complaints and more.

It is not cost-effective to make manned measurements for durations of longer than a few hours, and this often raises the question; How do you know if you have a good measurement and you are measuring the sound you thought you were?

To assist with this Audio recordings are often recorded in parallel with sound levels to help identify the source of the noise. However, it is time consuming to listen to and analyse these recordings and they can also be inconclusive.

Advances in signal processing has meant that sound level meters can process far more information than previously possible. Norsonic have introduced a 9-channel microphone for environmental measurements to help automate the location of noise sources. Eight of the channels are MEMS microphone devices which are phase matched. The delay in the signal reaching the microphones enables a location to be identified in a horizontal and vertical orientation. This 3D functionality enables, for example, aircraft to be picked out from normal community noise.

The 9th channel is a standard class one system which has type approval to ensure your overall sound levels are certified with the highest levels of accuracy.

The system uses PoE so a single LAN connection powers the system and collects all the data directly from the Lan port of the Norsonic 145 sound level meter. Data can be downloaded locally and displayed in software or the complete measurement can be analysed in the NorCloud system using the 4G/ wifi connectivity built into the Nor145 sound level meter. Nor Cloud has been developed to visualise the direction of the sound. The system has a sector display and it identifies resulting markers and directional alerts can also be set. Using this, LAeq is easily calculated for sound coming from the site of interest only. This enables efficient and accurate analysis without expensive time on site.

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