Question

A siren produces a sound intensity level of 90 decibel at a distance of 8.0 m.

assume that the siren acts as a point source of sound.

a. What is the sound intensity at a distance of 6.0m from the siren?

b. What is the power of the sound emitted by the siren?

c. What is the sound intensity level at a distance of 16.0 m from the siren?

Answer 1

a. For 8 m:

$$L_8=90-20\log(8/6)=88\text{ dB}.$$

b. The power of the sound:

$$P=10^{90/10}P_0=0.001\text{ W/m}^2.$$

c. For 16 m:

$$L_{16}=90-20\log(16/6)=81\text{ dB}.$$