In the PPD practice exam 1 there is a acoustic question that I can’t figure out how to solve it. In a nutshell “There are two identical fans that together produces 60 dB of sound. If one of the fans is removed, then the new dB level will be 57dB”.
Here is the question explanation “Reducing sound intensity by half reduces it by 3 dB. 60-3=57” but it still doesn’t make sense to me.
Can anyone explain to me how this works? Is there a formula?