Question

Chapter 17, Problem 095 The sound intensity is 0.0070 W/m2 at a distance of 13 m from an isotropic point source of sound. (a) What is the power of the source? (b) What is the sound intensity 6.3 m from the source? (c) What is the sound level 13 m from the source?

Answer #1

Sound intensity at a distance of 13 m from the source =
I_{1} = 0.007 W/m^{2}

Initial distance = R_{1} = 13 m

Power of the source = P

P = I_{1}(4R_{1}^{2})

P = 4(0.007)(13)^{2}

P = 14.866 W

Sound intensity at a distance of 6.3 m from the source =
I_{2}

New distance = R_{2} = 6.3 m

I_{1}(4R_{1}^{2})
= I_{2}(4R_{2}^{2})

I_{1}R_{1}^{2} =
I_{2}R_{2}^{2}

(0.007)(13)^{2} = I_{2}(6.3)^{2}

I_{2} = 0.0298 W/m^{2}

Sound level at 13 m from the source = _{1}

_{1} =
98.45 dB

a) Power of the source = 14.866 W

b) Sound intensity 6.3 m from the source = 0.0298
W/m^{2}

c) Sound level 13 m from the source = 98.45 dB

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