Sound control in Holmestrand library gave good publicity in Jarsberg newspaper

In connection with our assignment for Holmestrand Library, was Jarlsberg Avis in place to make a report.

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Text and photos by Magnus Franer-Erlingsen / Jarlsberg Avis

ECODEMPING: Fredrik Lerdahl and Espen Thoresen from the Norwegian Acoustics Centre have ensured better sound conditions for Tone Kjelling and others who work in or use the library.

Now the staff at the desk can more easily hear what you're saying to them

HOLMESTRAND: Sound is a special phenomenon. The librarians have realised this this summer.

“Kirkeklang” i bystyresalen og kjøkkenstøy i skranken har irritert brukere og ansatte på biblioteket. Men nå skal problemene være i ferd med å forsvinne.

- "I've heard everything the café staff have said in the kitchen, but not what's being said here at the counter," says librarian Tone Kjelling. Various machines in the café are also said to have contributed to the noise level.

Annoyance
"Both staff and visitors have experienced the acoustics in parts of the library as problematic," explains library manager Berit Borgen.
- There has been too much sound, not least in the multi-purpose room where the political meetings are now held. It was not unexpected that there would be acoustic challenges in such a large room, which absorbs a lot of sound.
- But this was becoming an annoyance, so we just had to get on with it," says Borgen.

That's why Fredrik Lerdahl and Espen Thoresen from the Norwegian Acoustics Centre came to the library on Thursday, "armed" with no less than 27 boxes packed with sound damping panels. On Friday, they finished the first part of the assignment.

- We have measured reverberation and noise in the room, and the results are far above the requirements set by the Labour Inspection Authority for the working environment. There is no doubt that it has been very demanding to sit at the counter. But we're getting that sorted out now," explains Thoresen.

SOUND-ABSORBING: This is what the discs look like. Here from the multiroom, where the city council meetings take place. Photo: Magnus Franer-Erlingsen

Has had an effect
Now, the white - and rather anonymous - sound-absorbing panels cover large parts of the ceilings and upper parts of the walls. "The panels absorb sound waves and prevent them from bouncing back as an echo," Lerdahl and Thoresen explain. And it has had an effect.
- In the multiroom, there was between one and a half and two seconds of echo - comparable to the sound conditions in old churches. "The difference is that churches were meant to have a lot of reverberation. But now almost all the reverb is gone from here," says Thoresen and demonstrates.

For the newspaper's reporter, the sound conditions now resemble a radio studio - in other words, little disturbing echoes.
- In the foyer, we measured the echo at 1.12 seconds. It's now down to 0.87 seconds. But we will return with other types of panels - oval "rafts" that hang from the ceiling, and then the echo will be further reduced in the foyer as well," they say.
- "I immediately notice that there is less noise," confirms Tone Kjelling at the counter.

Little known
Lerdahl and Thoresen are employees of a fast-growing company. Hafrsfjord-based Norsk Akustikksenter almost doubled its turnover from 2015 to 2016. They are therefore used to working in large, open spaces with many hard surfaces: "Problems with sound are something people tend to know little about, which is why many people live with sound problems without doing anything about it. This doesn't just apply to workplaces, we also often visit modern functional houses," says Thoresen.

It also turned out that the library had ordered more discs than they needed, so other municipal buildings can now make use of them," says Berit Borgen.