Sound intensity – the intensity of an acoustic wave is a measure of its energy. It is equal to the average value of the acoustic energy that flows through a surface area of 1 m² per second. For accurate measurement, it is important that the surface is oriented perpendicular to the direction of the acoustic wave propagation.
The unit of measurement for sound intensity in the SI system is W/m², which means watts per square meter.
There is a minimum value of sound intensity that will be audible to humans. It is 10^-12 W/m². If the sound has a lower intensity, it will automatically be too quiet for the human ear to perceive. On the other hand, when the value of the acoustic wave we receive exceeds 1 W/m², we will encounter the pain threshold. Such intensity is too strong for our ear, which instead of distinguishing sounds, begins to react with pain.
Below are the formulas for calculating the intensity of an acoustic wave:
I = W / t x S
I = P / S
where:
I – intensity of the acoustic wave in W/m²
t – time in seconds
S – surface area in m²
P – power of the sound wave expressed in watts (W).
