[SOLVED] Do decibels add?

[barnyard80]

If I buy two 15db case fans and put them on the front of my PC, will the total noise be 30db, 15db, or somewhere in between?

 

[jay32267]

The short answer is no....they don't add.
It will be somewhere in between.

Here is the information on how they are added.

https://www.engineeringtoolbox.com/adding-decibel-d_63.html

 

[RealBeast]

If I buy two 15db case fans and put them on the front of my PC, will the total noise be 30db, 15db, or somewhere in between?

No decibels are on a logarithmic scale. Going from 15dB to 25dB would be 10 times the sound intensity, and would be perceived to be 4 times as loud.

You have to add the log values, so 15dB + 15dB = 18dB. A 3dB increase would sound roughly 25% louder.