Does the noise level add up?

Question

Audio

for example, there is a 20db cooler and another 20db. will i hear 40db or a little over 20? how it works.
if the question is stupid, then sorry. It's just that there are 5 places for fans in the case and I can't believe that they are noisy at 100 dB

Answer 1

https://studopedia.info/9-9154.html

Answer 2

See how the noise level is calculated with specific examples: here .