Shamanic healing derives much of it's power from melodies, which arrive in the shaman as he or she enters a "dream state" (a different brain wave pattern), connecting with spirits and guides from other dimensions. These melodies are then sung or chanted as a prescription to heal the person. There is no distinction between physical, mental and emotional dis-ease, and so healing takes place in a holistic manner.
In Australia, the Aborigines use an ancient instrument called the didgeridoo for healing. With it's distinctive low tones, it sends vibrations of sound into the body of the person with an illness, thus affecting and changing the frequency of disharmony to the frequency of vibrant health.
In western culture, the oldest inquiry into sound as a healing modality goes back over 100 years in Germany. Modern physicians in Germany and Austria incorporate sound healing tables into their practices. In the United States, physicians such as Dr. Mitch Gaynor are renowned for being both well trained in western medicine and open to so-called "alternative" approaches as sound healing. Dr. Gaynor is a highly reputable oncologist who uses all the tools that western medicine has to offer his cancer patients, but he doesn't stop there. In addition to chemotherapy, he offers sessions using crystal bowls as a tool to entrain the brain. When the brain's frequencies match those of the bowls, the patient feels calmer, more hopeful, and more positive. These feelings then induce a cascade of chemical responses in the body, which increase the immune system's ability to deal with cancer cells.
I am hopeful that in the future, modalities that use energy -- frequency and vibration - will be the first approach to healing, with drugs and surgery standing by as a back up plan.