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
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
[tex]I = \frac{P}{A}[/tex]
[tex]= \frac{34}{4 \pi ( 44m )^ 2}[/tex]
= 0.00139 W / m 2
b) sound intensity level at position of micro phone is
[tex]\beta = 10 log \frac{I}{I_o}[/tex]
where I_o id reference sound intensity and taken as
[tex]= 1 * 10^{-12} W / m 2[/tex]
[tex]\beta = 10 log\frac{0.00139}{10^[-12}}[/tex]
= 91.456 dB
