The technique of harmonic kiss was invented by Bernard Dubreuil in the year 1987 and was developed by Tran Quang Hai through application in the field of music therapy. The technique of harmonic kiss is an application of waves in physics and is currently utilized in the field of music therapy as a healing process in psychology. This article explains the principle behind the technique in detail.
When one sings or speaks one sets up acoustic oscillations that resonate in one’s mouth and nose-throat cavity. This can be considered as a fancy wave of saying that one sets up sound waves that have a reinforcing effect on one another as the waves reflect from the surfaces of the cavity. These are basically standing waves and the lowest frequency of these waves is the fundamental and the higher frequencies being the higher harmonics.
An unusual way of singing occurs when the mouth-throat cavity of the second person is utilized to capture the sound waves from the singer’s mouth. The second person has the ability and power to then amplify a part of the harmonics that are captured, through widening and narrowing of his mouth that changes the shape of the resonating cavity.
The harmonic kiss can be considered as a technique of overtones that enables two individuals to produce overtones even if they are not an expert in this technique. One person produces a u sound and the second person then catches this sound in his mouth while his breathing is stopped that is used as an external resonator. Through the modification of the volume of this resonator, one can hear two or three overtones (H2, H3, and H4).