When electrical power is fed to a transducer, it is converted into mechanical power. The resultant physical movement disturbs the air, displacing it from its ambient, or resting state. The disturbance propagates outward in the form of pressure waves. The waves produce sound if the the amplitude and bandwidth fall within the sensitivities of a hearing system in the wave’s path.
The electrical to acoustical conversion efficiency is of interest. A 100 percent efficient transducer would produce one acoustic watt from one electrical watt.
The sound power, in acoustic watts, describes the total radiated sound energy, and is independent of distance or pattern control. It’s significance is that it produces all of the sound fields that develop in a room. In a reverberant space, both the direct and reverberant sound fields are the result of the sound power. It is good sound system design practice to achieve the desired LP using as little sound power as possible.