Thread: Wall Mounted Dust Extraction Fan

Originally Posted by Colin62

But 3dB more is double the sound.

I have recently been taking some dB readings at my local Men's Shed in preparation for adding some additional DE capacity.

Concern has been expressed by some members about the location and additional noise that another DE would add to the shed. Comments like... "will it be louder or quieter than x machine?" indicate that the noise level will be a factor in the decision making.

I've been doing some reading to try to understand what the comfort and hearing risk might be for members. One thing that has become clear to me is that the 'perception' of loudness varies between people for any particular dB reading and frequency profile. The SPL dB reading may indicate a doubling of sound power/pressure, but how old ears with varying degrees of industrial deafness detect loudness and how their brains perceive it is another thing.

Furthermore, that increases of 3dB, 6dB and 10dB double the sound level are all correct, in their own way.

Here is a nice simple summary of the difference between what the meter is reading and what the human hears...

https://conradaskland.com/blog/decib...volume-change/

...and here is academic support for how the frequency component changes the 'perception' of loudness. In my household I hear the low rumble of a visiting car arriving, which my wife never hears, but she hears the beep on timers that I often miss. This difference in hearing range and perception is relevant to both the low rumble of a DE impeller unit and also the corresponding higher pitched hiss of air at intakes.

Sound Measurement

For practical purposes I'm saying to the chaps at the Shed that... each increase/decrease of between 6dB & 10dB doubles or halves noise level to the human ear... which is near enough for their purposes.

The truth of the matter is that some of the equipment at the shed will be much louder than the DE, about which I can do little other than make them aware of the recommended exposure levels and encourage the use of ear protection. But will try to do as much as I can about the DE installation to minimise its contribution to the overall noise levels in the shed.