# how do i measure Sones?



## gregzoll (Dec 25, 2006)

It tells you on the Brohn website. It is basically about the decibel level. If it is loud, it means that yes it could be pulling more air, but makes you deaf. The quieter it is, does not always mean that it has enough power to exhaust the room.

As for 6" duct work, I have only seen that with commercial units that use a remote fan unit.


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## anon125 (May 23, 2014)

the specs say 6inch ductwork.
thanks


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## Bud9051 (Nov 11, 2015)

I roughed in a Broan and it also has the 6" duct option. It also came with a 6 to 4 converter but my run was easy.

Are the dampers open and are there many 90° turns? Mine will be awhile before I power it up, but a 0.3 zone fan I would expect to be very quiet. A rental store might have a sound meter. Might be worth a call. 

Bud


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## anon125 (May 23, 2014)

I guess one elbow then straight to the roof.
apparently 6 to 4inch adapter is a bad idea. or else they would come with a 4 inch hole!


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## joecaption (Nov 30, 2011)

Is there the needed 1" gap under the door?


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## SPS-1 (Oct 21, 2008)

The spec sheet on the fan has all ratings at .1 " of H2O, which is pretty much zero backpressure. So I would figure the bigger the ducting, the less the backpressure, and the quieter the fan. As the other guy mentioned, might be able to rent a sound level meter. Ratings will likely be in decibels on the meter. You can do a Google search to get a rough conversion. Specs don't say how far the microphone is when the sound was measured (so I guess that makes the spec rather worthless). On other types of equipment, I have more commonly seen sound level spec'd at 1 meter or 2 meter. 
If they want to be a-holes, they could always say that .3 sones is with .1" of backpressure, and if your application has more backpressure, the rating is invalidated. 
I have a Broan fan. I consider it a 1985 Hyundai, not a Lexus.


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## gregzoll (Dec 25, 2006)

Also you have to factor in the size of the room for makeup air, to help keep the steam down. 110 CFM may not sound a lot. But the larger the turbine and duct, the faster it can pull out the steam from the space.

"One sone is roughly equal to the sound of a refrigerator running. Normal conversations take place at about 4 sones, and light traffic rates up to around 8. Use sones to compare units, but be aware that the higher the CFM, the higher the sone rating is likely to be."

So figure that at 3/10's less than 1 Sone, you are talking about a pretty quiet unit at about 26.245 Phons.

"The loudness of N = 1 sone is equivalent to 40 phons, which is the loudness level
of LN = 40 dB of a sine wave (sinusoid) with a frequency of f = 1000 Hz."

"For loudness level LN < 40 phons: loudness L in sones = (LN / 40)2.86 − 0.005 LN in phons.

For loudness N < 1 sone: loudness level LN in phons = 40 × (N + 0.0005)0.35 N in sones.

According to Stanley Smith Stevens' definition, 1 sone is equivalent to 40 phons, which is defined as the loudness level of a pure 1 kHz tone at LN = 40 dBSPL, but only (!) for a sine wave of 1 kHz and not for broadband noise.

There is no "dBA" curve given as threshold of human hearing. "dBA" has absolutely noting to do with sone, or with phons, or sound pressure level in dB.

60 phons means "as loud as a pure 1000 Hz tone with a level of 60 dB.""


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## gregzoll (Dec 25, 2006)

This should help to place that fan in a better scale. It is a little above a whisper. Of course a room like a bathroom with a lot of surfaces, is going to amplify the sound.

There are free db meter apps for both iOS and Android OS. They do at least give you some reference at a C weight, what you are looking at.


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## ChuckF. (Aug 25, 2013)

Take the grating off and listen, sometimes the gratings can sing like tuning forks, or they can vibrate against the ceiling. Look inside and make sure that none of the casing parts are vibrating against anything. Make sure the tucked away wiring isn't rattling.

With the fan off, reach in and spin the squirrel cage by hand and see if it is rubbing on anything. They tend to be plastic and can deform easily.


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## anon125 (May 23, 2014)

Broan XB 110 fan is what we were told was good. specs say <.3sones.
thanks all
I have a sound file of the loud noise. but do not see how to post it!


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## gregzoll (Dec 25, 2006)

anon125 said:


> Broan XB 110 fan is what we were told was good. specs say <.3sones.
> thanks all
> I have a sound file of the loud noise. but do not see how to post it!


Do not need it, since your ears are picking up the echos, which are amplifying the fan when it is running, if the door is closed. If you whisper in the bathroom, you would be surprised how much louder it sounds, then in another room.

Hard surfaces are why sound engineers hate dealing with.


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## anon125 (May 23, 2014)

UH UH door is wide open and far louder than <.3 sone.
thanks


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