And the point here is that unlike this case, where you have a linear relationship, the relationship between the pressure and the liquid mole fraction isn't linear.

In operation, the motor structure operates as a linear motor, causing radiating surface 14 to vibrate along a axis of motion 22 (hereinafter "axis"), radiating pressure waves.

Based on the compressibility of liquid, through the mechanical mean can translate the small linear displacement into higher pressure.