Brekke and Strand Acoustics AS, in cooperation with the Norwegian Public Roads Administration (NPRA), has developed Lyttelab, our own acoustic laboratory located in our offices in Oslo.

The objective is to be able to listen to the noise when developing new road projects and other types of projects that generate noise and sound, in order to provide reliable information for decision-makers and interested parties. By providing the opportunity to listen to and compare both the current situation and the future situation, we want to provide predictability for the neighbours who will be affected by the measure, and reassure then about what they can expect in the future. Normally, noise zone maps are calculated and displayed as illustrations for new road routes or other noise events, but how well is the change communicated in the noise image? Now we can listen to the noise maps, both as the noise exists today, and how it will appear in the future.

Lyttelab can also be used as an aid in selecting solutions during a design phase. It will now be possible to conduct blind listening tests for the various proposals for a solution.

The method:

In order to synthesize sound for a situation, the estimated noise level at a specified listening point is used as a basis. The noise level is calculated using the Nordic calculation method or other relevant calculation standards. Nord2000 or equivalent is also used to calculate a frequency spectrum for the noise at the listening point. The result of the calculations forms the basis for the further synthesis of the sound. Real recordings of vehicles or other noise sources are used to generate new, complex soundscapes that are appropriate for calculation point in question. We take into account both how the road or noise source(s) are located in the terrain, how the terrain is shaped in the vicinity of the selected listening points, and the traffic's composition and speed on the relevant section or other source assumptions.

The room:

Lyttelab was established at Brekke and Strand's premises in Oslo, Norway. A room was constructed that can handle the acoustic requirements for listening, without being disturbed by other sounds or other visual impressions. Carpet is used on the floor, mineral wool sound-absorbers are used on the ceilings and panelling is used on the walls to give the room the desired acoustic properties. 

Lyttelab can also be transported to other geographical locations and presented, for example, in a cinema. Thus, Lyttelab can help to provide confidence and a common understanding by communicating the experience of noise to many stakeholders.