From WebRef.org

Commonly referred to as the mean-square sound-pressure ratio, sound energy, or just plain energy, acoustic energy is the squared sound pressure (often frequency weighted), divided by the squared reference sound pressure of 20 FPa, the threshold of human hearing. It is arithmetically equivalent to 10^{LEV÷10}, where LEV is the sound level, expressed in decibels.
Source: http://www.volpe.dot.gov/acoustics/docs/1990-1999/1999-1.pdf

Sponsor: Shop NowBuy 1 get 1 Free