Posted by unknown on Saturday, March 12, 2011 at 11:14pm.
A stereo speaker represented by P in Figure 1322 emits sound waves with a power output of 130.0 W. What is the intensity of the sound waves at point x when r = 7.8 m? W/m2

physics  drwls, Sunday, March 13, 2011 at 3:13am
Divide the power by 4 pi r^2 to get then power per area (intensity) at distance r. I get 0.17 W/m^2
Then convert intensity to decibels with the usual logarithmic formula. It's pretty loud ... over 110 dB.
This assumes that the speaker radiates sound uniformly in all directions. Few speakers work that way.