How loud is 33 dBa?

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Bozo Galora

Diamond Member
Oct 28, 1999
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some of the cooling/hsf sites have sound files you can d/l and listen to for dif fans. 33 aint bad, but 60mm is worse than 80mm at that level because whine is higher pitched. a panafloH1 (not L1) is 32db and fairly quiet on an ax-7 or ax-478
 
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CrawlingEye

Senior member
May 28, 2002
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Originally posted by: FalseChristian
33 decibels is between whispering and normal conversation so it's pretty quiet.
Click to expand...

Not really. 33dBA is the constant, it's like having someone whispering to you while you're on the computer all the time...

It's up to the poster if they're comfortable with that kind of noise, though.

 
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CrawlingEye

Senior member
May 28, 2002
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Yes, but that doesn't put them in between whispers and normal conversation.
Decibels are logarithmic, not linear.
Perhaps you're getting confused with the fact that a double in wattage is a linear 3db increase in volume or something?

It's not applicable to this case though.
Another thing to take into account is the frequency the fan makes, as it will have quite an effect on how quickly the sound is dissipated.
 
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CBone

Senior member
Dec 4, 2000
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Originally posted by: CrawlingEye
Yes, but that doesn't put them in between whispers and normal conversation.
Decibels are logarithmic, not linear.
Perhaps you're getting confused with the fact that a double in wattage is a linear 3db increase in volume or something?

It's not applicable to this case though.
Another thing to take into account is the frequency the fan makes, as it will have quite an effect on how quickly the sound is dissipated.
Click to expand...

What difference does it make if it is logarithmic? If you are using the same scale as JackMDS posted, 33 still lies between 15 and 60, making it between a whisper and normal conversation. Not 2x louder than a whisper and half as loud as normal conversation, but still qualifying for between status. ;)

CBone
 
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CrawlingEye

Senior member
May 28, 2002
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Originally posted by: CBone
Originally posted by: CrawlingEye
Yes, but that doesn't put them in between whispers and normal conversation.
Decibels are logarithmic, not linear.
Perhaps you're getting confused with the fact that a double in wattage is a linear 3db increase in volume or something?

It's not applicable to this case though.
Another thing to take into account is the frequency the fan makes, as it will have quite an effect on how quickly the sound is dissipated.
Click to expand...

What difference does it make if it is logarithmic? If you are using the same scale as JackMDS posted, 33 still lies between 15 and 60, making it between a whisper and normal conversation. Not 2x louder than a whisper and half as loud as normal conversation, but still qualifying for between status. ;)

CBone
Click to expand...

Umm, it's a HUGE difference between linear and logarithmic.
Paraphrase: It uses an algorithm, not direct steps.

It's not 1+2 = 3
It's more like 1+2=4

Here's an example:

The lagorithm of 400 to the base of 20 is 2.
Meaning, if you go from a volume of 2db to a volume of 20db you're actually getting a volume increase of 400%.
 
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dew042

Platinum Member
Nov 2, 2000
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Originally posted by: snow patrol
just ordered 4 12db papst 80mm fans to go in my case :)
Click to expand...


12db + 12db = 15db
15db + 15db = 18db

and so on.... it certainly adds up quickly.

dew.
 
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Mavrick007

Diamond Member
Dec 19, 2001
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I don't think noise is additive cause I'm sure a real loud fan would drown out the lesser sounding ones.
Ie. get something that is close to 40-45db and I'm sure you wouldn't hear the 12db fan :D
 
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Neurofreeze

Member
May 12, 2001
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I disagree with HowStuffWorks on conversation dB. 60dB is mighty loud.

Perceived sound is on a log(10) scale, meaning a 10dB increase is perceived as twice as loud as before. If you really, really want to know how one sound will add up with another, you have to convert the dB rating into Sound Pressure Level or Sound Intensity Level, which is a linear scale. There's also a problem of certain wavelengths cancelling out others or even amplifying others, but in a computer fan scenario, that stuff won't happen.

dB = 10log(I/(10^-12)) is the formula for Sound Intensity Level, relative to the human threshold of hearing (0dB @ 30,000N/m^2, I believe).

So to convert a dB rating to SIL, it'd be:

(10^(dB/10)) * (10^-12) = I

Convert all dB values individually to SIL, then add all SIL (I) values up, then just plug it back into the original equation. Doing this by SPL is slightly more complicated, but gets the same result, so I won't bother posting that.

Also, like it was said before, you have to account for the fact that the human ear is much more sensitive to higher pitched sounds than lower pitched sounds, so a high pitched 30dB sound will seem louder to you than a low pitched 30dB sound.

33dB, for total system sound, is pretty good (although I prefer something =< 30dB total). For one sound source, it's... well, it's better than most stock stuff (the retail AMD heatsink fan is something like 34-38dB I've heard, stock Lian Li case fans are 34dB at full power).
 
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CrawlingEye

Senior member
May 28, 2002
262
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Erm, one question, how do you intend to figure out the SPL of a fan?
SPL generally speaks for the efficiency of a speaker, not how loud a fan is.

Granted, you could define a pressure level, but that's not to say that it really serves much of a purpose in this scenerio. :p
 
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MatthewF01

Senior member
Mar 1, 2002
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06/02/2002 8:50 AM

33 decibels is between whispering and normal conversation so it's pretty quiet.

-------------------------


so, then its like many people having quiet conversation inside your computer ;)



hehehhe
 
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CrawlingEye

Senior member
May 28, 2002
262
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Originally posted by: MatthewF01
06/02/2002 8:50 AM

33 decibels is between whispering and normal conversation so it's pretty quiet.

-------------------------


so, then its like many people having quiet conversation inside your computer ;)



hehehhe
Click to expand...



You didn't read what has been said, did you?
It's not between, let alone discussing the accuracy of that chart.
 
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CrawlingEye

Senior member
May 28, 2002
262
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Originally posted by: Bob151
Originally posted by: snow patrol
just ordered 4 12db papst 80mm fans to go in my case :)
Click to expand...

Thats pretty low. Is that db rating normal for 80mm fans?
Click to expand...

Certainly not! My Vantec Stealths are 21dBA, which are known for being some of the quietest case fans.
I bet he's only pushing like 15CFM, though. =\

If you just want something to cool down your case (and don't care about noise) get the Vantec Tornado.
They're 80mm fans that are 84.1CFM but also 55.2dBA.


84.1CFM's as much air displacement as nearly 3 of my Stealths would produce, but it also has the dBA rating to match the performance...

 
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skriefal

Golden Member
Apr 10, 2000
1,424
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I bet he's only pushing like 15CFM, though.
Click to expand...

Those Papst fans push 19cfm each. Not bad for 12dBA! If only they weren't so expensive here in the US, I'd order a few...
 
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CrawlingEye

Senior member
May 28, 2002
262
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Originally posted by: skriefal
I bet he's only pushing like 15CFM, though.
Click to expand...

Those Papst fans push 19cfm each. Not bad for 12dBA! If only they weren't so expensive here in the US, I'd order a few...
Click to expand...

If you want something that you can't even hear, get the Vantec Stealths.
27CFM and only 21dBA, which is inaudible.

I had it out of my case when I was installing it, turned on, with my ear next to it. I could only hear the fan with my ear directly next to it.

It lowered my ambients a good 2c or so. (I only have one right now, I'm ordering my other Stealth tomorrow, the reason for my profile is because I'm lazy) :)

 
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skriefal

Golden Member
Apr 10, 2000
1,424
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81
I use the Panaflo L1A fans. Cheaper than the Stealths, and also rated at 21dBA (and 24cfm). People who have both have stated that the L1A is noticeably quieter than the Stealth, despite the dBA ratings.
 
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CBone

Senior member
Dec 4, 2000
402
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Originally posted by: CrawlingEye
Originally posted by: CBone
Originally posted by: CrawlingEye
Yes, but that doesn't put them in between whispers and normal conversation.
Decibels are logarithmic, not linear.
Perhaps you're getting confused with the fact that a double in wattage is a linear 3db increase in volume or something?

SNIP
Click to expand...

What difference does it make if it is logarithmic? If you are using the same scale as JackMDS posted, 33 still lies between 15 and 60, making it between a whisper and normal conversation. Not 2x louder than a whisper and half as loud as normal conversation, but still qualifying for between status. ;)

CBone
Click to expand...

Umm, it's a HUGE difference between linear and logarithmic.
Paraphrase: It uses an algorithm, not direct steps.

It's not 1+2 = 3
It's more like 1+2=4

Here's an example:

The lagorithm of 400 to the base of 20 is 2.
Meaning, if you go from a volume of 2db to a volume of 20db you're actually getting a volume increase of 400%.
Click to expand...

OK. And? If you are using the same reference and increase 100%, 213% and 400%, why wouldn't the 213% be between the 100 and 400? I mean if it is linear, 213 is still between 100 and 400. If it is a log scale, 213 is still between 100 and 400. If 33 dB is less powerful than 60 dB and more powerful than 10 dB, how could it not be between them?

CBone
 
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Gog

Senior member
Feb 1, 2002
351
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In real life, the sound of 33 DBa is somewhere between the sound of one hand clapping and me passing gas about six feet away from you:D, so its not too bad....
 
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