im too stupid to figure this out....can u help me out?

[falconx88]

if you have two fans blowing at 30 dba what is the combined total dba?

what is the formula for your answer? how to use this formula for 3 or even 4 fans at dif dba's..

if u can answer this i will call u god

 

[Viperoni]

If you 2 of the same fans, same noise level, it doubs.
3db is a doubling of volume....
so 1 30dn fan plus another 30db fan = 33db.

I dont know about different leve/more fans though.

 

[Wangel]

Remember that DBA is like turning up the volume on your stereo. Actually thats a good example. Think of each fan as a radio with the volume on 30. Think of two radios now, both with their volume on 30. The volume didn't go up, it's still at 30. But, if you have two fans now running at 30, it's like two speakers in your room (stereo) with 30 coming out of each one. If the speakers are right next to each other, (like the fans) you really won't notice any difference. Now what happens when one speaker is set to 40, and all the other speakers are set to 30. Well, you will hear the 40 speaker (fan) which will drown out the smaller volume speakers (fans).

My suggestion as far as fan noise goes is:

Use the quietest fans you can buy (heck, their cheap) but making sure they pass enough air (cfm), including some safety factor!

God? Can a man be a god to be worshipped? If I performed a magic trick, perhaps pulling a rabbit out of my hat, would that now make me a god? If I wrote a book and named it after one of my friends, perhaps the book of Jim, would that then make me a god?

BTW - my wife already thinks I'm a god! (Who said a fan club requires more than 1)

 

[falconx88]

wangle:

im sure you would hear the speaker with volume of 40 compared to the 30 but suppose you had one speaker at 40 vs one speaker at 40 and anther at 30...the latter one would be considered louder than the ohter one. I would like ot know the combined noise level for different fans. Since i would need to figure out the combined noise level produced in side my computer case!

 

[wyvrn]

There has to be a formula for this. Where are you Math/Physics majors?

 

[MereMortal]

The deciBel scale is a logarithmic scale of the form
Sound Level (in dB) = 10 log (I1/I0),
where the intensity level I1 is measured w.r.t. some reference intesity I0 (generally the lower limit of human hearing). If you have more than one source of sound, you add the intensities, of form I = 10^(Sound Level/10).

Hence you get
Combined Sound Level = 10 log [10^(fan1/10)+10^(fan2/10)+10^(fan3/10)+...].

So as Viperoni stated, for 2-30 dB fans, you get 33 dB total, and for 3-30 dB fans you get 34.8 dB, etc.

Of course, the average dB ratings given for fans don't include the noise you will get from vibrations induced in the case itself.

 

[Sparty]

GO STATE

 

[MereMortal]

I was at the game last night. It was an a$$-stomping!