Acoustic camera as ultrasmart assistant
The exact source of disruptive noise in buildings is often very difficult to find. Therefore, construction engineers and experts are increasingly relying on the help of acoustic cameras.
The sound is a cheat and a deceiver. As simple as it is to us humans to perceive it, it is so difficult to find its exact origin. What seems to come from the top left in a building actually often comes from the bottom right. What is suspected of coming from behind a wall covering ultimately comes across the floor and the much-maligned leaky window is often not the expected source of the noise, because it comes – for example – through the exhaust duct.
For Thomas Seidel, such sound puzzles and the accompanying surprising solutions are his daily bread. The managing director of the civil engineering company Krückl-Seidel-Mayr & Partner specialises in sound measurements in construction, industry and trade. Accordingly, he has many stories to tell, which prove: Acousticians often have to work as creatively as detectives.
For example, he says, this sound-absorbing door was a real masterpiece, perfectly produced, properly installed and yet in practice everything but soundproof. At the time, he spent many hours measuring and tinkering, remembers Seidel, until the source of the error was located: "In the end, we came across the fact that the spy hole in the door was not properly glued to the door, that it formed a joint and the sound could pass through that joint".
Supplement: "These are things that you can't see from the outside" so it takes a lot of time to discover them. Today, says Seidel, however, the tricky case would have been solved a little faster. "With an acoustic camera that visualises the sound, such issues can now be found relatively easily".
Seidel has been using an acoustic camera for some time now, namely the P132 sound scanner from Seven Bel. A handy device, the great advantage of which, in addition to saving time, is the possibility of detecting sound sources without destruction – for example, when it comes to leaking construction joints. If we had suspected that such a joint could be the reason for the noise in the past, the only way to confirm this was often to go and look. "And then perhaps to conclude it was not this joint" Seidel added sarcastically.
And if you didn't have to completely destroy it, it was very often necessary to dismantle complex panelling before the exact source of the noise could be located. Even the case in which Seidel used the Seven Bel sound scanner for the first time would probably have ended with extensive dismantling work without the scanner.
Also understandable for laypersons
"It was a much too loud seminar room at the time", explains Seidel. "You could also tell with your naked ear that the disturbing noises came from the ventilation. But what exactly was the cause? Was it the supply air? Was it the exhaust air? Or were there intrusions behind a wall covering?" With the help of the P132, Seidel was able to locate the problem quickly and very precisely.
An important point, he points out: "Because if you can't determine the exact source of the problem, you run the risk of reworking the wrong components" or, and this happens time and time again, you replace everything immediately, because it is impossible to limit the source of the sound within a reasonable time frame. "Testing, calculation and experience can solve many sound problems even without an acoustic camera, but this is much more complex”.
In addition, visualisations provided by acoustic cameras are immediately intuitive for everyone, whether they be laypersons or professionals. Complicated calculations and abstract evidence are usually not. That's why, Seidel finds a sound scanner an important aid, even if he can already be quite certain of the source of the problem from experience. Because the scanner provides objective, comprehensible proof. This means many lengthy disputes can be avoided in advance, especially with regard to liability issues.