How do you find the total power output when given the average intensity level of 110 dB and the distance of 15m?

Question

stormfire1 · Answer

http://en.wikipedia.org/wiki/Sound_power

jamesj · Answer

Ok, so let $ P_s $ be the power level of the source.  Then by definition, we write the decibel level of that source is
$$ L_s = \log_{10}(P_s/P_0) $$
where $ P_0 $ is a reference power source of $ 10^{-12} \ Watts $.

jamesj · Answer

Now, as the sound wave from the source expands, it expands in a spherical shell of area $ A = 4\pi r^2 $ and the power level is modified to
$$ P = P_s + 10 \log_{10}(A) $$
Now solve these equations using the information in your problem.

jamesj · Answer

*apologies, I should have written in that last equation, the L for decibel level equation
$$ L = L_s - 10\log_{10}(A) $$
Clearly the farther you go out, the higher the r, the greater the area A over which the sound is spread, the lower the decibel level L.

anonymous · Answer

thanks