Calculating Sound Intensity 24 m from a Loudspeaker

[Jtappan]

Homework Statement

The sound level 24 m from a loudspeaker is 66 dB. What is the rate at which sound energy is produced by the loudspeaker, assuming it to be an isotropic source?

____W

Homework Equations

?

Something to do with Intensity?

The Attempt at a Solution

I don't know where to begin on this problem. My book doesn't describe any problems that are related to distance nor does it have any equations that are related to distance.

 

[mezarashi]

This tests your understanding of "sound intensity", nature of sound propagation, and a bit of math.

What is sound intensity? What are its units? (hint: W/area).

At 24 meters, what is the surface area if sound radiates isotropically (i.e. like an expanding sphere).

You'll have to convert from the dB to linear scale to get power in Watts.