The major European MONICA project with participants from nine countries in total has moved a step closer to its goal. It did so recently when a group of researchers from DTU Electrical Engineering moved their tests from the protected lab environment to Refshaleøen, the Copenhagen island where, among other events, the big rock and metal festival COPENHELL is held each year.
At Refshaleøen, the researchers set up a test system with a total of 30 large speakers. 10 of the speakers were at the front, acting in the same way as the speakers used by a band to warm up the crowd. Behind the fictional crowd area was a new series of 20 speakers designed to ‘swallow’ some of the sound so that it would not reach the area behind the crowd. The area where neighbours typically feel bothered.
“It was so exciting to take our set-ups out into the real world and test them under some of the same conditions that we can find at open-air concerts. We got excellent measurement results, proving that our theses are holding up and that it is possible to reduce sound in the ‘Dark Zone’ behind the audience”, says Diego Caviedes Nozal, PhD student at DTU Electrical Engineering, a member of the team of 8.
Measurement data used as model input
As the weather was excellent during the measurement session, the researchers have yet to see how the set-up works under strong wind or rain conditions.
But the team successfully got more than 100 measurements with a total of 20 microphones at different locations in each of the two zones—the crowd area and the neighbouring area behind.
Data from the many measurements will be used over the coming year to design the first version of a model that will be used to adapt sound levels to different conditions.
“Our next measurement venues will be the Kappa Futur festival in Turin, Italy, in early July and Friday Rock in Tivoli, Copenhagen, in late August. Data from these measurements will also enrich the future model. The long-term idea is that the model should be able to ‘keep up’ and change settings when, for example, the temperature drops so that the speed of sound changes. This way, we can best eliminate noise nuisance for neighbours under different wind and temperature conditions,” says Diego.
Another major challenge is to take into account the geometry of the area with different buildings and other elements that can affect the sound waves. But Diego describes the initial results of their tests at Refshaleøen as very promising and hope that they can have a model on the table sometime during 2019.