Answer:
decibels (dB)
Explanation:
The sound intensity level is a quantity derived from the sound intensity.
The intensity of a wave is defined as the power of the source of the wave divided by the area through which the power of the wave is spread, mathematically:
[tex]I=\frac{P}{A}[/tex]
where
P is the power of the source
[tex]A=4\pi r^2[/tex] is the surface area over which the wave spreads (assuming that the wave propagates in all directions, it corresponds to the surface area of a sphere of radius [tex]r[/tex], where r is the distance between the source of the wave and the observer)
For sound waves, the intensity is often expressed using another unit, called decibel (dB), defined as follows:
[tex]\beta(dB)=10Log_{10}(\frac{I}{I_0})[/tex]
where
[tex]\beta[/tex] is the sound intensity level in decibels
I is the intensity of the sound wave
[tex]I_0=1\cdot 10^{-12} W/m^2[/tex] is the threshold intensity of a sound that a person can normally hear.