The net pressure exerted on a surface or interface by an acoustic wave. One might presume that the back-and-forth oscillation of fluid caused by the passage of an acoustic wave will not exert any net force on an object, and this is true for sound waves normally encountered. (The sound power of a normal speaking voice is less than one-millionth of the electric power of a 100-W light.) Intense sound waves, however, can exert net forces in one direction of sufficient magnitude (proportional to the sound intensity) to balance gravitational forces and thus levitate an object in air. These acoustic forces, generated by acoustic radiation pressure, are generally not of the magnitude to lift a table off the floor, although such is not inconceivable.