From sound therapist and instructor, Vicki Gould,
"The science behind sound therapy looks at frequencies. Every living thing has its own unique frequency, from an organ in your body to your own thoughts and feelings. When something goes wrong it means that the frequency has become disrupted and sound therapy can rebalance those frequencies by using different tones (musical notes) or by singing certain songs. The most basic example of this is using a tuning fork. If you place a tuning fork on one side of a glass and then tap it, you will find that water in the glass starts to vibrate at the same frequency as the tuning fork."

Since the human vessel contains more than 70% water, sound healing works by changing the molecular structure of the water in our bodies back to its native frequency.