How to attenuate low frequency extractor fan noise nuisance

How to attenuate low frequency extractor fan noise nuisance

How best to attenuate low frequency extractor fan noise nuisance, especially where the noise sounds like a hum or drone? The common solution is to fit a silencer / attenuator into the ductwork and install acoustic enclosures, screens or louvres. However these noise solutions usually only achieve a small reduction in low frequency sound. Most companies are unaware that there is a specialist type of solution available that uses advanced technology to provide a much higher reduction in low frequency extractor fan noise.

This 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 from the fan or blower, 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 low frequency extractor fan noise nuisance from a bakery in the food industry. Residents were complaining about a very loud hum sound which caused considerable annoyance at houses spread over a wide area around the factory. The loudness of the fan hum oscillated up and down considerably, which made it highly annoying. When the local Environmental Health Officer told the bakery that he had received noise nuisance complaints, the bakery realised that the loud hum was caused by a fan in their oven area. The food company first tried to attenuate their oven combustion air supply fan by fitting a silencer to the intake. This did not reduce the sound at the houses at all. So they asked us to help.

There were about 11 fans within the bakery oven area so we used a detailed diagnostic noise survey and analysis to identify the cause of the extractor fan noise nuisance. We very quickly found that the highly irritating hum causing the nuisance was created not by the combustion blower as suspected by the bakery, but by two cooling fans located on top of the bakery oven. These are shown in the above photo.

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 dB (decibels), making the hum completely inaudible at all the houses, even at night.

Afterwards residents were so relieved that the highly annoying fan hum had gone that many of them wrote to the Environmental Health Officer saying they could no longer hear the noise and thanking him and the bakery. He passed these thanks onto the bakery company.

Our advanced technology, high performance noise solutions can be applied to all types of industrial fan and blower and all types of factory as well as fans and blowers in any medium to large sized commercial company.

To find out how we can help you attenuate low frequency extractor fan noise nuisance, click help to suppress fan noise or ring the number below.

For more information and examples on how to attenuate extractor fan noise and a low frequency hum sound from fans and blowers, see cancelling low frequency fan noise.

For help with a noise problem contact us
or call us on 01727 864667