How much louder is 30dba vs 21dba?

[Grendel99]

I'm asking becuase I'm trying to quiet my case down. I know it's louder but how much louder? I have 2 x 80mm Panaflo L1A's (21dba apiece) in the front and the same in the back of my case. Say I added one 120mm Panaflo L1A in the front (30dba), would that be quieter? I always hear that 120mm fans are quieter than 80mm fans. Is that true? I would like to get more airflow with less noise if that's possible.

Thanks

 

[Olias]

The dB scale is logarithmic and non-linear where doubling you dB's you may quadruple your loudness. To answer your question about one 30dB source being louder than two 21dB sources, I too would like to know.

 

[CubicZirconia]

Try here to calculate dba's.

 

[Grendel99]

21dba + 21dba = 24dba. But like I said, I have heard that 120mm fans are quieter than 80mm's. And if it isn't that much louder than I would like to put the 120 in just for more airflow.

 

[skriefal]

21 dBA vs 30 dBA... that an 8x increase in emitted noise level. In other words, it'd take eight 21dBA fans to produce the same amount of noise as a single 30dBA fan.

But... the human ear doesn't hear linearly. Thus 30dBA will sound only about twice as loud as 21dBA, even though it's technically 8x as noisy.