Answer:
intensity of sound at level of microphone is 0.00139 W / m 2
sound intensity level at position of micro phone is 91.456 dB
Step-by-step explanation:
Given data:
power of sound P = 31 W
distance betwen microphone & speaker is 42 m
a) intensity of sound at microphone is calculated as


= 0.00139 W / m 2
b) sound intensity level at position of micro phone is

where I_o id reference sound intensity and taken as

= 91.456 dB