Sound Intensity
The amount of energy that is transported past a given area of the medium per unit of time is known as the intensity of the sound wave.
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The mathematical relationship between intensity and distance is sometimes referred to as an inverse square relationship.
Decibel Scale
Since the range of intensities that the human ear can detect is so large, the scale that is frequently used by physicists to measure intensity is a scale based on powers of 10. The scale for measuring intensity is the decibel scale.