# dB (dBa) and Sone: How do they relate?



## somody

Quote:


Originally Posted by *Highly-Annoyed*
Hello All,

I am looking into getting a better cooling solution for my ATi 9800 Pro, as it only has stock cooling at the moment and this is hindering my overclocking efforts.

I have found two worthy contenders; the VF700-Cu and the ATI Silencer 1 (Rev. 2). Both of these look good and I have heard good things about both. My main concern (other than price) is how noisy the fans on these coolers are. The only problem is that the VF700-Cu shows its noise emission in dB (which I have a sense of the sound of) but the ATI Silencer 1 (Rev. 2) shows its noise emission in "sone", which I don't really understand. Now the ATI Silencer 1 (Rev. 2) gives the definition of "sone" here in somewhat subjective terms. For example: "nearly inaudible in a computer case" is highly relative to many factors and not nearly as definitive as it should be. What would help, would be if I could find some relation between "sone" and dB (or dBa). For Example if I knew that "1 sone" = 25dB (or dBa) I would have a better feeling for how comparatively noisy each VGA coolers fan was.

If anybody can show a relation between these two types of sound measurement, or can provide a link to a web page/site that does, I would be *rep*pingly grateful!

Thanks.

Highly-Annoyed

here's a quote from Wikipedia:

Quote:

The sone is a unit of perceived loudness after a proposal of S. Smith Stevens in 1936. In acoustics, loudness is a subjective measure of the sound pressure. One sone is equivalent to 40 phons, which is defined as the loudness of a 1 kHz tone at 40 dB SPL. The number of sones to a phon was chosen so that a doubling of the number of sones sounds to the human ear like a doubling of the loudness, which also corresponds to increasing the sound pressure level by 10 dB, or increasing the sound pressure by a factor 3.16 (= root of 10). At frequencies other than 1 kHz, the measurement in sones must be calibrated according to the frequency response of human hearing, which is of course a subjective process. The study of apparent loudness is included in the topic of psychoacoustics.

To be fully precise, a measurement in sones must be qualified by the optional suffix G, which means that the loudness value is calculated from frequency groups, and by one of the two suffixes F (for free field) or D (for diffuse field).


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## Pauli

db is not the same thing as dba. A dba is a measurment to more accurately measure the loudness, db is the log based measurement which isn't what you think. EG 30db is not double the noise of 15db, its many times more.

And a good quote from http://www.madsci.org/posts/archives...9124.Eg.r.html :

Quote:

The problem with the sone measurement is, as britannica says, it is a
subjective measurement. That means it is based on individual human
judgement, as opposed to the decibel where we actually measure sound
pressure or power differences scientifically. Scientists can adjust the
decibel scale to match more precisely what humans hear by "A-weighting"
their decibel measurements, which involves excluding certain portions of
the measurement that are known to have a smaller effect on human hearing.
A-weighted measurements (dBA) are generally lower in value than the
original unweighted decibel measurement (dB). It would be very difficult
(based on the definition of 1 sone = 1000Hz tone at 40 dB)to relate the
sone to decibels. If I had to approximate (very loosely), I would guess
that if 1 sone = 40 dB, and we add three decibels every time we double the
amount of sound, we would get (very) roughly the following:

1 sone = 40 dB
2 sones = 43 dB
3 sones = 44.7 dB
4 sones = 46 dB

HOWEVER

This would be a starting point only!! If I were testing I would run tests
myself to determine the actual sound pressure or power in dB with a sound
meter. The conversions above would almost surely be inaccurate for the
following reasons:

Fan noise contains more than just a 1000 Hz tone. (Humans are very aware
of tones. A fan which is quiet but emits all its sound in a single tone is
usually considered 'louder' than a louder fan distributing its 'noise'
over a wide range of frequencies.

Humans may or may not perceive twice as much sound pressure as twice as
loud (most likely you would not).

As an engineer I am very cautious whenever we consider human feelings in
an experiment. Even when an engineer structures an experiment, she/he
must be very careful not to incorporate their own bias into the tests.
For example, if someone wanted a quiet fan and had to pick from two very
similiar fans in sound output, they may say that the fan which is better
looking is the quietest when in fact the ugly one may be slightly quieter.

Additionally, when we make scientific measurements of sound we usually do
so to a 'standard'. A standard is an accepted way of conducting the tests
so that if you and I both conduct the same tests to the same standard in
different times and places we should get approximately the same result. I
am unaware of a standard for sone measurements. It would be interesting
to note if the fan manufacturers state something like "3 sones using XYZ
standards" or some such thing. Without a standard comparisons don't mean
much.

So after all this, the bottom line is use the sone for approximation only,
and use a sound meter to determine the actual output in decibels. There
really isn't a conversion or correlation between the two, except at 1 sone
= 1000 Hz @ 40 dB.


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## Highly-Annoyed

Quote:


Originally Posted by *somody*
here's a quote from Wikipedia:

Thanks for looking this up. I'm not quite sure I follow it all, but I appreciate you putting in the time to find it for me. Rep for you!

Quote:


Originally Posted by *Pauli*
db is not the same thing as dba. A dba is a measurment to more accurately measure the loudness, db is the log based measurement which isn't what you think. EG 30db is not double the noise of 15db, its many times more. And a good quote from http://www.madsci.org/posts/archive...49124.Eg.r.html :

This quote seems to explain the relationship between sone and dB pretty well, namely that (other than 1 sone) the relationship is somewhat subjective. Perhaps, ignorant as I am of such things, I simply asked for a relationship between sone and dB or (dBa) when really there is no definitive mathematical correlation between the two, no formula with which to convert one into another. It would seem that, essentially, even though they both deal with measuring "sound" or "noise", one is a precise scientific measurement and the other is subject to opinion, therefore only allowing a "rough" correlation at best. At least thatâ€™s how I read it anyway...









Thanks for looking this up for me; your help is much appreciated. Rep for you too!

Thanks to all who contributed!

Highly-Annoyed


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## Muhahahaha

Lol, I know this thread is old, but others may be interested in the answer. This thread was the second result when I did a google search, haha, but the first result had the answer.

Go here and scroll down to "Sone to dBA cannot be converted linear." However, the accuracy is only +/- 2 dBA, which corresponds to +/- 58% in noise level.









Yes, dBA is also a log-based scale.









Edit: Actually, the table and the formula given below it don't match! Use the formula, as I have seen it on other sites as well.

So yeah, there's really no reason to visit that site then. The formula is: *dBA = 33.22 * log(sones) + 28*. Reversing this, we get *sones = 10^[(dBA - 28) / 33.22]*, lol.









(The log is base 10).


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## ms4runr

www.sengpielaudio.com/calculatorSonephon.htm
This will give you the comparison between sones and dBA.


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