It is well known that sound energy decreases with distance traveled.
Attenuation is the decrease of sound intensity with distance.
Natural materials, however, all produce an effect which further weakens the sound. The combined affect of scattering and absorption is attenuation . Attenuation of sound is generally proportional to the square of sound frequency. Attenuation itself is often not of intrinsic interest, however, natural properties and loading conditions can be related to attenuation. Attenuation often serves as a measurement tool that leads to the formation of theories to explain physical or chemical phenomenon which decrease the ultrasonic intensity.