A unique sound environment laboratory was built in 2006. It is located at the Occupational and Environmental Medicine, Sahlgrenska Academy at University of Gothenburg. The laboratory enables studies on how different sound environments affect us humans, with well-controlled conditions, for example noise from different types of transportation, ventilation noise, interaction between sound environment and visual environment and between sound and vibrations. The effects we assess mainly relate to general noise disturbance and sleep disturbance, effects on speech communication, learning, recovery, emotional states, and work performance.
The lab has two floors. Upstairs is the control room with the sound system and four exposure rooms with very low background noise: three bedrooms and one larger exposure room where the interior can be adapted for the specific project. On the ground floor is a home-like apartment, which is used mainly by participants in sleep studies who live in the laboratory for up to a week.
The laboratory is specially designed with the goal that background noise level should be below the hearing threshold. Each exposure room is built as a separate module, which isolates the rooms from ground borne noise or vibration from the outside. The ventilation system is specially designed with the air coming from a damped, separate fan assembly located elsewhere in the building. In the rooms, the air diffuses silently. The background noise level from the ventilation is very low, about 13 dBA. The acoustic features of the rooms are specially designed to obtain as evenly distributed a sound field as possible. The walls are slanted to reduce regular sound reflections and several hundred speakers are placed in walls, ceilings and corners to be able to produce a sound field that spreads evenly. The sound is controlled digitally from a separate control room and the system provides good conditions for simulating widely differing sound environments.
You can find more detailed information on the acoustic properties of the laboratory (report in Swedish): Sound laboratories - verification of sound fields (pdf)