What is the wave intensity formula for sound?

[CoolGod]

Our physics teacher gave us a formula to calculate intensity, she didn't really specify what intensity, it should be related to sound.
I = intensty
A = amplitude
P = Density
F = frequency
V = velocity
pi = 3.14
she said I = 2*(pi)^2*A^2*P*F^2*V
I can't find anything like this in books or internet, maybe I'm bad at searching.
I was wondering is she right and can she explain the formula? I get the simple I=P/A formula.

 

[nasu]

This is the formula for the intensity of a plane wave with amplitude A, and frequency f, propagating with speed v.
You can find a complete derivation of the formula here

http://physics.info/intensity/

or just look up "intensity plane mechanical wave" or similar.

 

[Greg Bernhardt]

Formula to calculate intensity: I = V/A Where: I = intensity V = voltage A = area of the conductor Example: Calculate the intensity of the current in a 16 cm wire carrying a current of 2.0 A. Solution: I = V/A = 2 A = area of the conductor = 16 I = 2/16 = 0.125