Page 5 - Vibrations-2
P. 5
Looking at Noise
What has this got to do with noise?
Most white noise sources have a Normal distribution.
When you perform spot measurements on a noise signal,
they will have a Normal distribution with regards to their
amplitude.
=
2
= =
Very often when you measure the
mean of a white noise source it is
zero, whereas the mean squared is
always positive. Power measurement is therefore directly
proportional to the square of the voltage signal from the
2
noise sensor. Sound intensity has units of a Watts/m .
Sound intensity = where p is the pressure and v the
particle velocity.
When the noise source is a single
point,
() =
4 2
P is the sound power.
4
