Question

What is the intensity level of a sound with an intensity of 0.000127 W/m2?

65 dB

72 dB

81 dB

120 dB

Answer 1

dB = 10 log (I/Io)
Where, Io is the reference intensity which is the minimum intensity that human can hear.
That is; Io = 10^-12
Therefore;
dB = 10 log (0.000127/10^-12) =80.79
= 81 dB
Therefore; the correct answer is 81 dB