Practice Exam 1 - decibel change for half the sound


A question asked about to fans at 60 dB of sound.
If one fan is removed, what is the dB

The answer said half the sound would be a change of 3 dB, but I always read the change in half the sound is 10 dB.

I put 50 dB but the blackspecs answer is 57 dB. Can you please explain this to me?

@gloriaw92 sure thing!

When it comes to acoustics and having multiple fans with similar sound levels the equation that we would be looking at is Lt = Ls + 10log(n) where n = the number of fans, Lt = the total sound observed or 60dB and Ls is the decibel level of an individual fan. In our case the equation would look like 60dB = Ls + 10log(2) or Ls + 3 since 10log(2) = 3. Which translates to 60dB = Ls+3 or Ls = 57dB.

This works for 3 fans, 5 fans, 20 fans etc. as long as the fans are equal in sound intensity.

Hope this helps!