sound/decibel question......

[blurredvision]

Let me see if I can explain this correctly....... I am buying 4 case fans that are rated at 25 dBA apeice. If I were to add 1 fan, that would add 25 dBA of noise to my case. So when I add 4 fans, does the noise added still rate at 25 dBA, or is it multiplied somewhat because of the multiple fans?

If this isn't understandable, I'll try to explain better.

 

[Ikonomi]

I read somewhere that adding another fan with an equal noise level will raise the overall noise by like 3 dBa or something. So like, if you have one fan at 25 dBa, and add another identical fan, your noise level will be 28. If you add another, it will be 31 dBa.

I didn't come up with this, but that's what I read on some hardware page. I'll try to find it, but if I don't, and if this is wrong, don't blame me. I didn't do it. :Q

 

[BornStar]

That's right. If you double the number of fans, the sound goes up by 3. So you will be looking at 31dB.

 

[BD2003]

Its a lot more complicated than that...but last time I read 6db is a doubling of volume (some places ive seen them say 10db). Just because you have 4 25dba fans, doesnt mean its going to necessarily be 4 times as loud. The sound waves will interfere and overlap to a degree, and it should be a bit louder, but not THAT much louder.

 

[sillymofo]

Why do you worry about a 25 dBA fan? Ambience noise is already average at 50 dBA.

 

[blurredvision]

Originally posted by: cr4zymofo
Why do you worry about a 25 dBA fan? Ambience noise is already average at 50 dBA.

I'm not really worrying about a 25 dBA fan, just trying to get this comp quieter than it is now. You don't understand how loud this thing is with stock fans. Stock anything usually isn't good as far as computers go .

 

[Eli]

Originally posted by: blurredvision

Originally posted by: cr4zymofo
Why do you worry about a 25 dBA fan? Ambience noise is already average at 50 dBA.

I'm not really worrying about a 25 dBA fan, just trying to get this comp quieter than it is now. You don't understand how loud this thing is with stock fans. Stock anything usually isn't good as far as computers go .

bah.

And whoever said that ambient noise is at 50dBA, there's no way. The Vantec Tornado 119CFM screamer is 56dBA, and it almost literally sounds like a hairdryer.

Maybe if you live right next to a highway or something.

 

[FrustratedUser]

Originally posted by: Ikonomi
I read somewhere that adding another fan with an equal noise level will raise the overall noise by like 3 dBa or something. So like, if you have one fan at 25 dBa, and add another identical fan, your noise level will be 28. If you add another, it will be 31 dBa.

I didn't come up with this, but that's what I read on some hardware page. I'll try to find it, but if I don't, and if this is wrong, don't blame me. I didn't do it. :Q

Correct answer!
3dB is double the noise. So for 4 fans that will be: 25 + 3 + 3 + 3 = 34dBA

 

[BornStar]

Originally posted by: FrustratedUser

Originally posted by: Ikonomi
I read somewhere that adding another fan with an equal noise level will raise the overall noise by like 3 dBa or something. So like, if you have one fan at 25 dBa, and add another identical fan, your noise level will be 28. If you add another, it will be 31 dBa.

I didn't come up with this, but that's what I read on some hardware page. I'll try to find it, but if I don't, and if this is wrong, don't blame me. I didn't do it. :Q

Correct answer!
3dB is double the noise. So for 4 fans that will be: 25 + 3 + 3 + 3 = 34dBA

Not quite. You double the sources for a 3dB increase. 1-2 = +3dB, 2-4 = +3dB so the final is 25+3+3=31.

 

[sillymofo]

Originally posted by: Eli

Originally posted by: blurredvision

Originally posted by: cr4zymofo Why do you worry about a 25 dBA fan? Ambience noise is already average at 50 dBA.

I'm not really worrying about a 25 dBA fan, just trying to get this comp quieter than it is now. You don't understand how loud this thing is with stock fans. Stock anything usually isn't good as far as computers go .

bah.

And whoever said that ambient noise is at 50dBA, there's no way. The Vantec Tornado 119CFM screamer is 56dBA, and it almost literally sounds like a hairdryer. Maybe if you live right next to a highway or something.

Yes, way. Just do a quick google search to find out what the average ambient noise level for a quiet suburb measures. The reason you notice a hair dryer is because its sound is emitting at a different frequency (different than ambient), therefore you are subject to listen to it all the time.

Think of it as the atmospheric pressure, you're used to walk around with all that weight pressing down on you. Now if you were a test tube baby and raised in a zero gravity environment, the sudden introduction to our everyday living environment would crush you to death. The reason you're living is because your body is used to balance the pressure inside to the outside.

 

[Ionizer86]

Yep, going from 25 to 35 dBa would be a 10x increase in intensity. On the log scale, 3 more points is about equal to a doubling of intensity. 1-->2 fans then 2-->4 fans is doubling the intensity twice, so 31dBa is pretty much where it's at.

As for psychology/perception, it's been said that it takes a 10x increase in intensity for perception to increase 2x. So it should only sound a bit louder going from 1 to 4 fans.

 

[blurredvision]

Too much math!!

Seriously though, thanks guys. Much appreciated. Glad I learned something in the process .

 

[FrustratedUser]

Originally posted by: BornStar18

Originally posted by: FrustratedUser

Originally posted by: Ikonomi
I read somewhere that adding another fan with an equal noise level will raise the overall noise by like 3 dBa or something. So like, if you have one fan at 25 dBa, and add another identical fan, your noise level will be 28. If you add another, it will be 31 dBa.

I didn't come up with this, but that's what I read on some hardware page. I'll try to find it, but if I don't, and if this is wrong, don't blame me. I didn't do it. :Q

Correct answer!
3dB is double the noise. So for 4 fans that will be: 25 + 3 + 3 + 3 = 34dBA

Not quite. You double the sources for a 3dB increase. 1-2 = +3dB, 2-4 = +3dB so the final is 25+3+3=31.

Oops, my bad.

 

[Howard]

Originally posted by: Ionizer86
Yep, going from 25 to 35 dBa would be a 10x increase in intensity. On the log scale, 3 more points is about equal to a doubling of intensity. 1-->2 fans then 2-->4 fans is doubling the intensity twice, so 31dBa is pretty much where it's at.

As for psychology/perception, it's been said that it takes a 10x increase in intensity for perception to increase 2x. So it should only sound a bit louder going from 1 to 4 fans.

25 > 35dBa is a perceived doubling of sound intensity.

 

[TechnoKid]

Isn't 25db kinda loud for a "quiet" pc? I have a chieftec aluminum case with some sunon fans, i really want to try the sonata case with some quieter fans than the sunon.