Sound power level is the acoustical energy emitted by the sound source, and is an absolute value. It is not affected by the environment. Motor Lw ratings are obtained from the determination of sound power levels generated by a motorwhen it is operated at no load. These sound power levels are obtained in accordance with IEEE 85. What is heard is a sound pressure level that is determined, for any particular location, by many factors, including size of the room, nature of its walls, ceilings, furnishings, etc. The pressure level at the point of hearing is also related to the distance from the sound source. The motor is the starting point, and when proper and accurate consideration is given to the other components of the system, sound power level ratings in octave bands will allow calculation of the resulting sound pressure levels in the space. 
     Sound power levels are connected to the sound source and independent of distance. Sound powers are indicated inIn addition to the sound pressure level, there are other levels expressed in decibels, so one must be careful when reading technical articles about sound or regulations on environmental noise. One such level is the sound power level (PWL or Lw), which identifies the total sound power emitted by a source in all directions. Sound power, like electrical power, is measured in watts.  In the case of sound, the amount of power is very small, so the reference selected for comparison is the picowatt (10-12 watt). The sound power level (in decibels) is defined as our website describes. Click into www.wowgold1000.com