It can be very difficult to find out how best to attenuate low frequency extractor fan hums and drones. The common solutions are to fit silencers / attenuators into the ductwork and install acoustic enclosures, screens or louvres. However these usually only achieve a small reduction in low frequency sound. Most companies are unaware that there is a specialist, advanced technology type of solution available that provides a much higher reduction in low frequency extractor fan noise than common solutions.
The specialist high tech type of solution can attenuate low frequency hum and drone sounds by such a large amount that it makes them completely inaudible to residents living in houses near the factory or commercial building where the fans are located. In contrast, common types of solution usually achieve some reduction in low frequency noise but often not enough to stop local residents complaining.
The above picture shows an example where the specialist high tech type of solution was used to attenuate the sound from two cooling extractor fans in the food industry. These blowers were producing a very loud hum sound that caused considerable annoyance to local residents over a wide area around the factory. The food company first tried to attenuate their combustion air supply fan by fitting a silencer to the intake. This did not reduce the sound at the houses. So they asked us to help.
Our sound survey quickly identified that the highly irritating hum was created not by the combustion blower but by two cooling fans located on top of the bakery oven. We also found that a large noise reduction was needed because the fan hum was very loud and the food factory operates at night. Our specialist advanced technology solution was used to attenuate the fan noise. This was highly successful, reducing the fan hum by 27 decibels, making the hum completely inaudible at all the houses, even at night.
For more information and examples on how to attenuate extractor fan noise and low frequency sound from blowers, look under “Industrial Noise Reduction” in the menu at the top of this page, or click on the contact us button.
Advanced Noise Solutions - example of how to attenuate extractor fan noise