I am finding out the relationship between intensity of sound and speed of sound. To do that, I am using this equation:
$$I =\frac{\Delta P^2_\text{max}}{2 \rho v}$$
where $\Delta P_\text{max}$ is pressure amplitude, $I$ is intensity of sound, $\rho$ is density of medium, and $v$ is wave speed.
I got this equation from this website, Physics.info,
my only problem is that I cannot figure out how to measure the pressure amplitude. How do I do that?
Best Answer
First of all, this question is more or less about the engineering and that would need another SE site. But since the answer is not complicated:
If you consider sound in "common, general meaning" (i.e. something that could be percieved by an ear) then the simpliest pressure meter is the microphone. OK, there are microphones sensitive to air pressure or air velocity, but from recorded signal you can always read the pressure variations. Common way to do that is to record a normalised signal 94 dB at 1 kHz which corresponds to 1 Pa.
From pressure variations to $P_{max}$ there is a simple way using RMS (root mean square, consult this), i.e. for a sine pressure wave of amplitude $A$: $P_{max}=\frac{\sqrt{2}}{2}A$.