Use our online Decibels Distance (dB) Calculator to find the sound intensity at a distance by knowing Initial distance and target distance from noise source. Sound pressure level is used to define the sound level. It is the ratio of absolute, Sound pressure and a reference level. According to inverse Square Law, the distance from the source of sound increases when the decibel level decreases. Decibel, shortly referred as (dB) is a logarithmic unit used in the measurement of intensity of sound level.