The VibraSonic is truly sound actuated, with a precise frequency range from 4 – 20,000 Hertz. The base plate is actually driven by powerful magnetic voice coils. This means you are moving up and down in pure sound waves, much like standing on powerful speakers.
In contrast, what traditional mechanical vibration plates actually have is a motor or several small  motors that runs at one selected speed and not the multiple sounds from a sound frequency generator or frequency software. The motion in these types of machines is transferred to the plate via mechanical actuation rods.