An apartment on the ground floor of a two story house in the city lies close to a busy road. The living room in the apartment is facing the road, and the inhabitants are bothered by traffic noise, especially in the morning and the afternoon, when the traffic is the heaviest.
Traffic noise could be clearly heard when standing in the living room. The facade facing the city street consists of a large window and a porch door. It was thought that the main contribution of noise came from these two parts, but it was difficult to verify if those assumptions were true, or exactly where any weaknesses in the structure might be located.
The Norsonic Nor848A-10 1.0m acoustic camera with 256 microphones was used for the recordings. The camera was placed inside the living room pointing at the facade facing the street. The living room would hence act as the receiving room, and the outside as the sending room, much in the same sense as the procedure for sound insulation measurements. Weaknesses in the facade would then be possible to be seen as small noise sources in the structure. It was possible to use regular traffic as sound source, regardless whether the traffic was steady, or just a single vehicle from time to time.
In addition to using traffic as noise source, measurements were made by placing a omnidirectional loudspeaker emitting white noise on the outside of the facade. This created a more stationary sound field on the outside of the structure, and made detection of small cracks and gaps in the structure even easier.
Initial recordings when using traffic as noise source displayed a single strongest facade weakness at the top left of the living room wall as seen from the video below. This strongest source position was also confirmed when using the omnidirectional loudspeaker as noise source. At this position a ventilation valve was installed, and most of the traffic noise came from this location.