NTi Press Release, 9. May 2018

Great Sound at Europe`s biggest Live Sound Trade Fair
The annual ProLight + Sound trade fair (PLS) in Frankfurt is acclaimed for Live sound demonstrations from top PA system manufacturers. This year the “Agora Live Sound Arena”, in the middle of the exhibition halls, was again a big attraction. While the various manufacturers presented their large-scale PA systems and latest stage equipment under realistic conditions at this open-air venue, the acoustic engineering company AMT, Isernhagen was responsible for protecting the public’s hearing according to the DIN 15905-5 standard. All sound level measurements were performed with the XL2 Sound Level Meter and visualized on the rather big screen using the Projector PRO software.
The Live Sound Arena was once again a crowd-puller this year. There is no doubt that, within reason, “louder is better” in such a comparative demonstration environment. AMT's job was to measure and display the sound levels, as well as advise the exhibitors on what is possible within the legal limits . For the sound level measurement, AMT chose the XL2 Sound Level Meter, because it is compliant, can integrate with the big screen, and provides a clear traffic-light color warning system.
Sound or Noise?
At such a significant music fair, visitors expect crystal-clear sound with rich bass even at high volumes, regardless of the genre of music played. In order to provide such a sound experience for the visitors without adverse health effects, and to offer the same conditions to each of the manufacturers in their fight for attention, the AMT acousticians pushed levels to the max during the audio presentations. “Maintaining the levels is important to get the job done properly. We aim at providing the best possible sound. This means that we have to respond flexibly to the different wishes of the exhibitors during the presentation, as each sequence is structured differently with speech and music components”, says Michael Oehlerking, Managing Director of AMT.
Since this Frankfurt trade fair is located in the city center, it is surrounded by public infrastructure and office buildings. This proximity creates special challenges with “loud events”. Thus, the sound systems had to be aligned in such a way that it was still possible to work relatively undisturbed in the offices of the neighboring buildings.
Level monitoring in open-air presentations
DIN 15905-5 prescribes the monitoring of the level values at the loudest position in the audience area. It is often not possible to measure at this position during the event. Therefore, the measurement microphone is placed directly in front of the speakers, e.g. hung in front of the line array. The correction values k1 and k2 between these two positions are then determined during setup with the XL2. During the event, the XL2 corrects the measured values and displays the live values. By optimizing the alignment of the speakers and the level limits, a compromise was found that suited the organizers, residents and the public.
”Because of the changing weather and the dynamic flow of visitors during the four days of the fair, we had varying conditions at the venue. Thanks to the professional technicians and good planning, these fluctuations could be well compensated”, Oehlerking proudly reported.
The feedback from the visitors was also very positive. The great demonstrations were enhanced by the big screens providing a mix of exhibitor information, live stream and sound level values.

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