Sound Level and Sound Waves

Question

The source of a sound wave has a power of 2.70 µW. Assume it is a point source. What is the sound level 2.1 m away?

Answer 1

Intensity Equation

I = power / Area = P / A = P / (4 pi r^2)

Where I is measured in W/m^2

Threshold of hearing is usually 10^-12

The loudness is calculated in dB and relates to the Intensity.

Decibel = B

B = 10 log ( I / (10^-12))

µ = E-6

Use the Intensity formula, then pop it in the decibel formula. Done.