The Formula for sound intensity is expressed as
P = sound power
A = area
In order to measure the sound intensity level, need to compare the given sound intensity value with standard intensity value.
The formula of Sound Intensity Level is expressed as
I = sound intensity and
Io = reference intensity
The unit of sound intensity is expressed in decibels (dB)
Solved examples on Sound Intensity
A person whistles with the power of 0.9 × 10-4 W. Calculate the sound intensity at a distance of 7m.
P = 0.9 × 10-4 W
A = 7m
Sound intensity formula is
I = P / A
I = 0.9×10−4 / 7
I = 1.28 x 10-5 W/m2
Determine the intensity level which is equivalent to an intensity 1 nW/m2.
Intensity Level formula is given by
IL = 10 log10 I / I0
I = 1 nWm-2 = 1 × 10-9 Wm–2
Io = 10-12 Wm-2
IL= 10 log10 (1×10−9) / 10−12
IL = 10 log10 103
IL = 30.