When the man was tested for the fitting of the device at the hospital, he was found to have no loss of hearing, and the hospital sent letters to both the specialist and the GP asking them to check their equipment. Now in this case what caused the hearing restoration was not so clearly defined. It may have been the person's own sound that was restorative, or exposure to the tones and overtones sounded in the course. It is in fact quite common that the work done on these courses has a positive effect on many apparently unrelated physical ailments. There is a definite correlation between the use of tone and overtones, the healing power of these sounds and the ability to experience one's full spectrum of sound with clarity.
Most common example is the chanting of the Tibetan monks.
Not to be confused with harmony, which is more then one singer blending their voices. It has within it the sound of temple gongs, and of laughter.