A building is a complex system with static and dynamic ingredients. Active or dynamic components may lead to an acoustic issue in a building or facility. Static walls, concrete ceilings and steel structures may conduct vibrations over long distances.
With the portable sound camera it is possible to do measurements in buildings, conference-rooms and more. Using the far field imaging, the source of disturbing sound is visualized. A leak in insulation or a defect in a sealing joint can be visualized by placing a high-frequent sound-source in the room and observe the spots where the sound can be heard outside the room.
The use of near field imaging in buildings is very well possible too, however when it comes to low frequencies, there are some considerations to be made. We will help you out with professional and objective advise.
ROOFTOP: AIR HANDLING UNIT
Engineering- and consultancy group Volantis has a clear focus on innovation, durability, safety, comfort and life-time performance. Volantis handles projects by looking at the situation from different perspectives.
This case describes a neighborhood that could not sleep well due to noise. An air handling unit was suspected to be part of the problem.
We supported Volantis with measurements to prove hypotheses and identify the root-cause.
Multiple measurements with were performed during one day. As it was possible to visualize noise differentiated to individual frequencies, the main noise source was identified soon. Counter intuitive but proven by facts, it appeared that the noise did not come from the air exhaust, but from the intake section!
Near field vibration measurements in the air-handling unit revealed that the motor-drive of the return fan generated vibrations. The sound transfer path was formed by the air intake-channel.
Knowing the system of source, path and sound, it took only minor modifications of the return fan and in a suspension of the air-intake channel. The noise problem is adequately and permanently solved!
Sorama products used: Sorama CAM1K & Sorama Portal.
LOW FREQUENT NOISE IN AN APARTMENT
After renovation of an apartment it appeared that a low-frequent noise was dominantly present.
The source was found in an on-site consultancy visit. Using the Sorama sound imaging products to scan the inner walls of the apartment, our consultant revealed vibrations in these walls. A 20-40Hz resonance of the walls was responsible for the high amount of sound-pressure. We found that the root-cause is the ventilation system, more specific in poorly balanced fan wheel. By decoupling the ventilation system from the inner walls, an improvement of 25-30 dB(A) was realized (!). Future replacement of a balanced fan will add another reduction of approximately 5-10 dB(A).
In 2011 the Italian company SIT and Sorama joined forces to develop solutions for a new silent boiler. The new designed and innovative SIT Integrated Combustion System, SunFlower, is applied for the first time.
Analyzing this compact boiler with Sorama Sound Imaging resulted in a quick learning curve. Valuable insights regarding possible noise reduction measures became evident. Specifically the insights on the dynamic behavior of the boiler system helped to reduce the overall appliance noise with nearly 5 dB(A).
See below near field images showing the vibration modes that were most interesting.