Sound, or vibrational patterns, need a medium through which to travel. We are accustomed to experiencing vibrational changes in pressure (i.e., sound) as they travel through air. However, sound travels five times more effectively through water than air (ever wonder why the pet store owners don't want us tapping on the glass of the fish tanks? :) and five times more effectively than that through a solid. Thus, sound travels through a solid twenty-five times better than it does through air.
In addition to this, low frequency vibrations travel through solids better than high frequencies. Consider the following example.
The top of the graph depicts a very slow, low level hum of 20Hz. This is just at the threshold of human hearing. These are the frequencies that you tend to feel more than hear. The bottom of the graph depicts a higher level frequency of 440Hz (or, A440 -- the most popular tone for tuning forks). Notice how many cycles there are in this tone compared to the long, sonorous tone above it. These fast cycles are easier to block by solid material, whereas the slower waves are both harder to block, and can actually be amplified and carried farther distances through solid material. (Now you know why you hear only the bass tones from the stereo system in the apartment above you instead of all the high-end treble and vocals. :)
Now, consider that the human body is 75% water and the rest is solid material. It is the perfect medium to transmit sound -- especially low level vibrations. We can use this to our advantage by vibrating the solid material of some structure, such as a sound therapy table. These vibrations are then transmitted through the fluids and solid mass of our body. By using recordings that are specifically designed with deep vibrational acoustic material, we can bath our bodies in a vibrational soundscape which, aside from health benefits, is extremely pleasurable and relaxing!